diff --git a/CHANGELOG b/CHANGELOG
index c9755fd..9e3af09 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,12 @@
+Version 0.7.3 (2007.03.08):
+	* added: the program shows some kind of errors itself
+	* added: checking whether an user has inserted a correct value of a variable or a function
+	* fixed: navigation from the keyboard
+	* changed: the esc key selects the entire input text now (in the input edit)
+	* added: a test when the program is being starded which checks if the coordinates of the
+      main window actually pointing at the valid area (for example when someone took
+      his configuration file into a new computer and the new computer has a smaller screen)
+
 Version 0.7.2 (2007.02.28):
 	* added buttons Sgn and Mod
 	* the button 'err' is active when there's actually an error now
diff --git a/TODO b/TODO
index 8b81704..e629aa7 100644
--- a/TODO
+++ b/TODO
@@ -1,12 +1,7 @@
 TODO TTCalc
 ===========
 
-* To add the test when program is being starded which checks if the coordinates of the
-  main window actually pointing
-  at the valid area (for example when someone take his configuration file into a
-  new computer)
 * To add some physical constants
 * To make the help 
-* To add navigation from the keyboard (in the two lists - funtions and variables)
 
 
diff --git a/src/Makefile b/src/Makefile
index f930729..2cd7e70 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -1,8 +1,6 @@
 CC     = g++
 o      = resource.o calculation.o functions.o iniparser.o languages.o mainwindow.o parsermanager.o programresources.o tabs.o variables.o winmain.o 
-CFLAGS = -Wall -pedantic -s -O3 -mwindows -mthreads -I../../../ttmath
-
-                                           
+CFLAGS = -Wall -pedantic -s -O2 -mwindows -mthreads -I../../../ttmath
 name   = ttcalc.exe
 dir_output = ../../output
 
@@ -24,20 +22,19 @@ ttcalc: $(o)
 resource.o: resource.rc
 	windres resource.rc resource.o
 
-calculation.o:			calculation.cpp compileconfig.h parsermanager.h resource.h programresources.h iniparser.h languages.h threadcontroller.h stopcalculating.h
-functions.o:			functions.cpp compileconfig.h tabs.h resource.h messages.h programresources.h iniparser.h languages.h threadcontroller.h stopcalculating.h
-iniparser.o:			iniparser.cpp compileconfig.h iniparser.h
-languages.o:			languages.cpp compileconfig.h languages.h
-mainwindow.o:			mainwindow.cpp compileconfig.h winmain.h programresources.h iniparser.h languages.h threadcontroller.h stopcalculating.h resource.h messages.h tabs.h
-parsermanager.o:		parsermanager.cpp compileconfig.h parsermanager.h resource.h programresources.h iniparser.h languages.h threadcontroller.h stopcalculating.h
-programresources.o:		programresources.cpp compileconfig.h programresources.h iniparser.h languages.h threadcontroller.h stopcalculating.h
-tabs.o:					tabs.cpp compileconfig.h tabs.h resource.h messages.h programresources.h iniparser.h languages.h threadcontroller.h stopcalculating.h
-variables.o:			variables.cpp compileconfig.h tabs.h resource.h messages.h programresources.h iniparser.h languages.h threadcontroller.h stopcalculating.h
-winmain.o:				winmain.cpp compileconfig.h winmain.h programresources.h iniparser.h languages.h threadcontroller.h stopcalculating.h resource.h messages.h tabs.h
+calculation.o:		calculation.cpp compileconfig.h parsermanager.h resource.h programresources.h iniparser.h languages.h threadcontroller.h stopcalculating.h tabs.h messages.h
+functions.o:		functions.cpp compileconfig.h tabs.h resource.h messages.h programresources.h iniparser.h languages.h threadcontroller.h stopcalculating.h
+iniparser.o:		iniparser.cpp compileconfig.h iniparser.h
+languages.o:		languages.cpp compileconfig.h languages.h
+mainwindow.o:		mainwindow.cpp compileconfig.h winmain.h programresources.h iniparser.h languages.h threadcontroller.h stopcalculating.h resource.h messages.h tabs.h
+parsermanager.o:	parsermanager.cpp compileconfig.h parsermanager.h resource.h programresources.h iniparser.h languages.h threadcontroller.h stopcalculating.h
+programresources.o:	programresources.cpp compileconfig.h programresources.h iniparser.h languages.h threadcontroller.h stopcalculating.h
+tabs.o:				tabs.cpp compileconfig.h tabs.h resource.h messages.h programresources.h iniparser.h languages.h threadcontroller.h stopcalculating.h
+variables.o:		variables.cpp compileconfig.h tabs.h resource.h messages.h programresources.h iniparser.h languages.h threadcontroller.h stopcalculating.h
+winmain.o:			winmain.cpp compileconfig.h winmain.h programresources.h iniparser.h languages.h threadcontroller.h stopcalculating.h resource.h messages.h tabs.h
 
 
 clean:
 	rm -f *.o
 	rm -f *.s
 	rm -f $(dir_output)/$(name)
-	rm -f $(name_cons)
diff --git a/src/compileconfig.h b/src/compileconfig.h
index f075684..c86036e 100644
--- a/src/compileconfig.h
+++ b/src/compileconfig.h
@@ -52,7 +52,7 @@
 */
 #define TTCALC_MAJOR_VER		0
 #define TTCALC_MINOR_VER		7
-#define TTCALC_REVISION_VER		2
+#define TTCALC_REVISION_VER		3
 
 
 
diff --git a/src/functions.cpp b/src/functions.cpp
index 485ec32..3c40ca4 100644
--- a/src/functions.cpp
+++ b/src/functions.cpp
@@ -90,7 +90,7 @@ int i;
 		}
 		else
 		{
-			EnableWindow(GetDlgItem(hWnd,IDC_EDIT_FUNCTION_NAME), false);
+			SendDlgItemMessage(hWnd, IDC_EDIT_FUNCTION_NAME, EM_SETREADONLY, 1, 0);
 			SetFocus(GetDlgItem(hWnd,IDC_EDIT_FUNCTION_VALUE));
 		}
 
@@ -204,12 +204,13 @@ const char * message;
 }
 
 
-BOOL WmTabCommand_AddFunction(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
+BOOL WmTabCommand_AddFunction(HWND, UINT message, WPARAM wParam, LPARAM lParam)
 {
-	caption = GetPrgRes()->GetLanguages()->GuiMessage(Languages::dialog_box_add_function_caption);
-	name    = "";
-	value   = "";
-	adding  = true;
+	HWND hWnd  = GetPrgRes()->GetTabWindow(TabWindowFunctions::tab_functions);
+	caption    = GetPrgRes()->GetLanguages()->GuiMessage(Languages::dialog_box_add_function_caption);
+	name       = "";
+	value      = "";
+	adding     = true;
 	parameters = 1;
 
 	if( DialogBox(GetPrgRes()->GetInstance(), MAKEINTRESOURCE(IDD_DIALOG_ADD_FUNCTION), hWnd, DialogProcFunction) )
@@ -236,8 +237,9 @@ return true;
 	(we're also using this method directly without using the main loop of messages)
 	(we don't define the 'lParam' parameter there)
 */
-BOOL WmTabCommand_EditFunction(HWND hWnd, UINT message, WPARAM wParam, LPARAM)
+BOOL WmTabCommand_EditFunction(HWND, UINT message, WPARAM wParam, LPARAM)
 {
+HWND hWnd = GetPrgRes()->GetTabWindow(TabWindowFunctions::tab_functions);
 HWND list = GetDlgItem(hWnd, IDC_FUNCTIONS_LIST);
 
 	if( ListView_GetSelectedCount(list) != 1 )
@@ -273,8 +275,9 @@ return true;
 }
 
 
-BOOL WmTabCommand_DeleteFunction(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
+BOOL WmTabCommand_DeleteFunction(HWND, UINT message, WPARAM wParam, LPARAM lParam)
 {
+HWND hWnd = GetPrgRes()->GetTabWindow(TabWindowFunctions::tab_functions);
 HWND list = GetDlgItem(hWnd, IDC_FUNCTIONS_LIST);
 int items = ListView_GetSelectedCount(list);
 
diff --git a/src/languages.cpp b/src/languages.cpp
index 1f4d13f..45e73b1 100644
--- a/src/languages.cpp
+++ b/src/languages.cpp
@@ -283,9 +283,10 @@ void Languages::InitGuiMessagesTab()
 		"\r\n"
 		"If you have any questions, advices or interesting ideas about"
 		" this program or if you want to join to this project as"
-		" the developer or programmer just contact with me."
+		" a developer or programmer feel free to contant with the author."
 		);
 	InsertGuiPair(about_box_title,			"About");
+	InsertGuiPair(about_box_button_close,	"Close");
 	InsertGuiPair(unknown_error,			"An unknown error has occurred");
 
 
@@ -389,9 +390,10 @@ void Languages::InitGuiMessagesTab()
 		"\r\n"
 		"Jeżeli masz jakieś pytania, rady, ciekawe pomysły dotyczące"
 		" tego programu lub chciałbyś dołączyć jako projektant/programista"
-		" poprostu skontaktuj się ze mną."
+		" poprostu skontaktuj się z autorem."
 		);
 	InsertGuiPair(about_box_title,			"O programie");
+	InsertGuiPair(about_box_button_close,	"Zamknij");
 	InsertGuiPair(unknown_error,			"Nieznany kod błędu");
 
 	
diff --git a/src/languages.h b/src/languages.h
index 13eb70d..ea8d461 100644
--- a/src/languages.h
+++ b/src/languages.h
@@ -122,6 +122,7 @@ public:
 		cant_init_common_controls,
 		about_text,
 		about_box_title,
+		about_box_button_close,
 		display_digit,
 		display_group_scientific,
 		unknown_error
diff --git a/src/mainwindow.cpp b/src/mainwindow.cpp
index 40dc5a9..940d033 100644
--- a/src/mainwindow.cpp
+++ b/src/mainwindow.cpp
@@ -45,6 +45,116 @@ namespace MainWindowFunctions
 {
 
 
+
+/*!
+	Loop through all the controls and remove the
+	dark border that the previous default push
+	button has.
+*/
+void ClearPushButtons(HWND hWnd)
+{
+HWND controls = GetWindow(hWnd, GW_CHILD);
+LRESULT dlg_code;
+
+	while(controls)
+	{
+		dlg_code = SendMessage(controls, WM_GETDLGCODE, 0, 0);
+
+		if(dlg_code & DLGC_DEFPUSHBUTTON)
+			SendMessage(controls, BM_SETSTYLE, (WPARAM)BS_PUSHBUTTON, true);
+
+		controls = GetWindow(controls, GW_HWNDNEXT);
+	}
+}
+
+
+/*!
+	this method checks whether 'button' is a push button and if so
+	sets it as the default push button (with black border)
+*/
+void CheckAndSetDefPushButton(HWND button)
+{
+	LRESULT dlg_code = SendMessage(button, WM_GETDLGCODE, 0, 0);
+
+	if(dlg_code & DLGC_UNDEFPUSHBUTTON)
+		SendMessage(button, BM_SETSTYLE, (WPARAM)BS_DEFPUSHBUTTON, true);
+}
+
+
+/*!
+	we're trying to get the next or previous control which should have 
+	the focus now
+*/
+HWND GetNextControl(HWND focus, HWND output_edit, HWND tab, WPARAM wParam)
+{
+	HWND next = 0;
+	bool shift = (GetKeyState(VK_SHIFT) & 0xffff0000) != 0;
+	bool direction_next = true;
+
+	// if an user has pressed 'up' or 'left' or 'tab'+'shift'
+	// that means we're going 'back'
+	if( wParam==VK_UP || wParam==VK_LEFT || (wParam==VK_TAB && shift) )
+		direction_next = false;
+
+	if( focus==output_edit && direction_next )
+	{
+		// if we are on the output edit and the direction is 'forward' 
+		// then the next control will be the 'tab'
+		next = tab;
+	}
+	else
+	if( focus == tab )
+	{
+		// if the tab control has the focus and an user has pressed 'left' or 'right'
+		// we allow the system to manipulate the focus
+		if( wParam==VK_LEFT || wParam==VK_RIGHT )
+			return 0;
+
+		if( direction_next )
+		{
+			// we're getting the first control on a specific dialog on the selected tab
+			int tab_sel = TabCtrl_GetCurSel(tab);
+			HWND tab_dialog = GetPrgRes()->GetTabWindow(tab_sel);
+			next = GetNextDlgTabItem(tab_dialog, 0, false);
+			ClearPushButtons(tab_dialog);
+		}
+		else
+		{
+			// if the direction is 'back' we're setting the focus onto the output edit
+			next = output_edit;
+		}
+	}
+	else
+	{
+		// we get here if the focus is not set on 'tab' neither
+		// on 'output_edit' with the direction equals 'forward'
+
+		// if an user has pressed the tab (with or without shift)
+		// or if the control with a focus doesn't want arrows key
+		// and the control isn't a radio button we're using 
+		// GetNextDlgTabItem to find the next element
+		LRESULT dlg_code = SendMessage(focus, WM_GETDLGCODE, 0, 0);
+		if( wParam==VK_TAB ||
+			((dlg_code & DLGC_WANTARROWS)==0 && (dlg_code & DLGC_RADIOBUTTON)==0) )
+		{
+			// the control returns from GetNextDlgTabItem will not be perfect
+			// we have to make a small change:
+			// when this method has returned 'output_edit' and when we're
+			// moving back and the focus it not set on 'tab' the focus
+			// should be set into the tab control
+			HWND nexttmp = GetNextDlgTabItem(GetPrgRes()->GetMainWindow(),
+											focus, !direction_next);
+
+			if( !direction_next && focus!=tab && nexttmp==output_edit )
+				next = tab;
+		}
+	}	
+
+
+return next;
+}
+
+
 /*!
 	this function sets the focus on a specific control
 	(the standard procedure from the operating system doesn't work well because
@@ -53,45 +163,25 @@ namespace MainWindowFunctions
 	remember to set WS_EX_CONTROLPARENT to the tab control and
 	to all dialog boxes on the tab
 */
-void SetNextFocus()
+bool SetNextFocus(WPARAM wParam)
 {
 	HWND next = 0;
-
 	HWND main_window = GetPrgRes()->GetMainWindow();
 	HWND focus       = GetFocus();
 	HWND output_edit = GetDlgItem(main_window, IDC_OUTPUT_EDIT);
 	HWND tab         = GetDlgItem(main_window, IDC_TAB);
-	bool shift       = (GetKeyState(VK_SHIFT) & 0xffff0000) != 0;
 
-
-	if( focus==output_edit && !shift )
-	{
-		next = tab;
-	}
-	else
-	if( focus == tab )
-	{
-		if( shift )
-		{
-			next = output_edit;
-		}
-		else
-		{
-			int tab_sel = TabCtrl_GetCurSel(tab);
-			HWND tab_dialog = GetPrgRes()->GetTabWindow(tab_sel);
-			next = GetNextDlgTabItem(tab_dialog, 0, false);
-		}
-	}
-	else
-	{
-		next = GetNextDlgTabItem(main_window, focus, shift);
-
-		if( shift && focus!=tab && next==output_edit )
-			next = tab;
-	}
+	next = GetNextControl(focus, output_edit, tab, wParam);
 
 	if( next )
+	{
 		SetFocus(next);
+		CheckAndSetDefPushButton(next);
+
+		return true;
+	}
+
+return false;
 }
 
 
@@ -646,12 +736,14 @@ return true;
 
 
 /*!
-	a user has pressed 'ESC' key in the main window
-	we're cleaning the input edit
+	an user has pressed 'ESC' key in the main window
+	we're setting the entire input edit as being selected
 */
 BOOL WmCommand_IDCANCEL(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
 {
-	SetDlgItemText(hWnd, IDC_INPUT_EDIT, "");
+	HWND iedit = GetDlgItem(hWnd, IDC_INPUT_EDIT);
+	SendMessage(iedit, EM_SETSEL, 0, -1);
+	SetFocus(iedit);
 
 return true;
 }
@@ -722,26 +814,21 @@ return true;
 }
 
 
+
+
 void CreateCommandMessagesTable(Messages & cmessages)
 {
-
-
 	cmessages.Associate(IDM_ALWAYS_ON_TOP, WmCommand_AlwaysOnTop);
 	cmessages.Associate(IDM_NORMAL_VIEW, WmCommand_NormalView);
 	cmessages.Associate(IDM_COMPACT_VIEW, WmCommand_CompactView);
 	cmessages.Associate(IDM_HELP_ABOUT, WmCommand_HelpAbout);
 	cmessages.Associate(IDM_NEW_WINDOW, WmCommand_NewWindow);
 	cmessages.Associate(IDM_CLOSE_PROGRAM, WmCommand_CloseProgram);
-
 	cmessages.Associate(IDC_INPUT_EDIT, WmCommand_InputEditNotify);
-
 	cmessages.Associate(IDM_EDIT_UNDO, WmCommand_EditUndo);
 	cmessages.Associate(IDM_EDIT_PASTE, WmCommand_EditPaste);
 	cmessages.Associate(IDM_EDIT_COPY_RESULT, WmCommand_EditCopyResult);
-
-
 	cmessages.Associate(IDCANCEL, WmCommand_IDCANCEL);
-
 	cmessages.Associate(IDM_LANGUAGE_ENGLISH, WmCommand_LanguageEnglish);
 	cmessages.Associate(IDM_LANGUAGE_POLISH, WmCommand_LanguagePolish);
 }
@@ -755,8 +842,10 @@ static Messages command_messages;
 		// initiation
 		CreateCommandMessagesTable(command_messages);
 
-
-return command_messages.Call(LOWORD(wParam), hWnd, message, wParam, lParam);
+	if( command_messages.IsMessage(LOWORD(wParam)) )
+		return command_messages.Call(LOWORD(wParam), hWnd, message, wParam, lParam);
+	else
+		return TabWindowFunctions::WmTabCommand(hWnd, message, wParam, lParam);
 }
 
 
@@ -846,13 +935,14 @@ char compiler[30];
 BOOL CALLBACK AboutProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
 {
 char * about_buffer;
+Languages * lang;
 
 	switch(message)
 	{
 	case WM_INITDIALOG:
-		SetWindowText(
-			hWnd,
-			GetPrgRes()->GetLanguages()->GuiMessage(Languages::about_box_title) );
+		lang = GetPrgRes()->GetLanguages();
+		SetWindowText(hWnd, lang->GuiMessage(Languages::about_box_title) );
+		SetWindowText(GetDlgItem(hWnd, IDOK), lang->GuiMessage(Languages::about_box_button_close) );
 
 		about_buffer = new char[2000];
 		CreateAboutText(about_buffer);
diff --git a/src/messages.h b/src/messages.h
index 06f88f0..bce5799 100644
--- a/src/messages.h
+++ b/src/messages.h
@@ -61,7 +61,7 @@ public:
 	}
 
 
-	BOOL Call(UINT key, HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
+	bool Call(UINT key, HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
 	{
 		MessageTable::iterator i = message_table.find(key);
 
@@ -71,6 +71,16 @@ public:
 	return i->second(hWnd, message, wParam, lParam);
 	}
 
+	bool IsMessage(UINT key)
+	{
+		MessageTable::iterator i = message_table.find(key);
+
+		if( i == message_table.end() )
+			return false;
+
+	return true;
+	}
+
 
 	bool Empty() const
 	{
diff --git a/src/programresources.cpp b/src/programresources.cpp
index cd100df..48d6627 100644
--- a/src/programresources.cpp
+++ b/src/programresources.cpp
@@ -545,6 +545,36 @@ std::string application_data;
 }
 
 
+void ProgramResources::CheckCoordinates()
+{
+	if( x_pos < -50 )
+		x_pos = 0;
+
+	if( y_pos < -50 )
+		y_pos = 0;
+
+	if( x_size < 100 )
+		x_size = 100;
+
+	if( y_size < 30 )
+		y_size = 30;
+
+	int cx = GetSystemMetrics(SM_CXSCREEN);
+	int cy = GetSystemMetrics(SM_CYSCREEN);
+
+	if( x_size > cx+10 )
+		x_size = cx;
+
+	if( y_size > cy+10 )
+		y_size = cy;
+
+	if( x_pos > cx-50 )
+		x_pos = cx - x_size;
+
+	if( y_pos > cy-50 )
+		y_pos = cy - y_size;
+}
+
 
 IniParser::Error ProgramResources::ReadFromFile()
 {
@@ -598,10 +628,12 @@ std::string ini_value[20];
 	always_on_top	= bool( atoi(ini_value[0].c_str()) );
 	view			= atoi(ini_value[1].c_str()) == 0 ? view_normal : view_compact;
 	maximized		= bool( atoi(ini_value[2].c_str()) );
+	
 	x_pos			= atoi( ini_value[3].c_str() );
 	y_pos			= atoi( ini_value[4].c_str() );
 	x_size			= atoi( ini_value[5].c_str() );
 	y_size			= atoi( ini_value[12].c_str() );
+	CheckCoordinates();
 
 	SetPrecision(	atoi(ini_value[6].c_str()) );
 	SetBaseInput(	atoi(ini_value[7].c_str()) );
diff --git a/src/programresources.h b/src/programresources.h
index ab22e98..6112377 100644
--- a/src/programresources.h
+++ b/src/programresources.h
@@ -279,6 +279,7 @@ private:
 	const char * SkipWhiteCharacters(const char * string);
 	bool IsDecDigit(int c);
 	bool SplitFunction(const std::string & input, const char * * name, int * param);
+	void CheckCoordinates();
 
 	ttmath::Objects variables;
 	ttmath::Objects functions;
diff --git a/src/resource.rc b/src/resource.rc
index 1696733..03a032d 100644
--- a/src/resource.rc
+++ b/src/resource.rc
@@ -50,29 +50,31 @@ BEGIN
   CONTROL "",1010,"SysTabControl32",WS_CHILD |WS_TABSTOP | WS_VISIBLE ,0,39,261,110, WS_EX_CONTROLPARENT
 END
 
-102 DIALOG 0, 0, 265, 61
-STYLE DS_FIXEDSYS |DS_SETFONT |DS_CENTER |WS_POPUP |WS_VISIBLE |WS_THICKFRAME |WS_CAPTION 
+
+102 DIALOG DISCARDABLE  0, 0, 358, 61
+STYLE DS_MODALFRAME | DS_FIXEDSYS | DS_CENTER | WS_POPUP | WS_VISIBLE | 
+    WS_CAPTION | WS_SYSMENU
 CAPTION "Add a new variable"
 FONT 8, "Ms Shell Dlg"
 BEGIN
-  CONTROL "Ok",1,"BUTTON",BS_DEFPUSHBUTTON |BS_VCENTER |BS_CENTER |WS_CHILD |WS_TABSTOP |WS_VISIBLE ,205,10,50,14
-  CONTROL "Cancel",2,"BUTTON",BS_PUSHBUTTON |BS_VCENTER |BS_CENTER |WS_CHILD |WS_TABSTOP |WS_VISIBLE ,205,28,50,14
-  CONTROL "",1134,"EDIT",ES_AUTOHSCROLL |ES_LEFT |WS_CHILD |WS_BORDER |WS_TABSTOP |WS_VISIBLE ,38,10,67,14
-  CONTROL "",1135,"EDIT",ES_AUTOHSCROLL |ES_LEFT |WS_CHILD |WS_BORDER |WS_TABSTOP |WS_VISIBLE ,38,28,147,14
-  CONTROL "name:",1136,"STATIC",SS_LEFT |WS_CHILD |WS_GROUP |WS_VISIBLE ,7,12,27,8
-  CONTROL "value:",1137,"STATIC",SS_LEFT |WS_CHILD |WS_GROUP |WS_VISIBLE ,7,30,27,8
+    DEFPUSHBUTTON   "Ok",1,291,10,50,14,BS_CENTER | BS_VCENTER
+    PUSHBUTTON      "Cancel",2,291,28,50,14,BS_CENTER | BS_VCENTER
+    EDITTEXT        1134,38,10,67,14,ES_AUTOHSCROLL
+    EDITTEXT        1135,38,28,230,14,ES_AUTOHSCROLL
+    LTEXT           "name:",1136,7,12,27,8
+    LTEXT           "value:",1137,7,30,27,8
 END
 
-103 DIALOG DISCARDABLE  0, 0, 273, 73
-STYLE DS_FIXEDSYS | DS_CENTER | WS_POPUP | WS_VISIBLE | WS_CAPTION | WS_THICKFRAME
-CAPTION "Add a new function"
+103 DIALOG DISCARDABLE  0, 0, 370, 74
+STYLE DS_MODALFRAME | DS_FIXEDSYS | DS_CENTER | WS_POPUP | WS_VISIBLE | 
+    WS_CAPTION | WS_SYSMENU
 FONT 8, "Ms Shell Dlg"
 BEGIN
-    DEFPUSHBUTTON   "Ok",1,205,10,50,14,BS_CENTER | BS_VCENTER
-    PUSHBUTTON      "Cancel",2,205,27,50,14,BS_CENTER | BS_VCENTER
+    DEFPUSHBUTTON   "Ok",1,303,10,50,14,BS_CENTER | BS_VCENTER
+    PUSHBUTTON      "Cancel",2,303,27,50,14,BS_CENTER | BS_VCENTER
     EDITTEXT        1144,46,10,67,14,ES_AUTOHSCROLL
     COMBOBOX        1146,46,29,67,130,CBS_DROPDOWNLIST | WS_TABSTOP
-    EDITTEXT        1145,46,47,210,14,ES_AUTOHSCROLL
+    EDITTEXT        1145,46,47,308,14,ES_AUTOHSCROLL
     LTEXT           "name:",1147,7,12,31,8
     LTEXT           "value:",1149,7,49,33,8
     LTEXT           "param:",1148,7,30,33,8
@@ -155,7 +157,7 @@ EXSTYLE WS_EX_CONTROLPARENT
 CAPTION "tab4"
 FONT 8, "Ms Shell Dlg"
 BEGIN
-  CONTROL "precision 1",1150,"BUTTON",BS_AUTORADIOBUTTON |BS_LEFT |WS_CHILD |WS_TABSTOP |WS_VISIBLE ,15,4,252,10
+  CONTROL "precision 1",1150,"BUTTON",BS_AUTORADIOBUTTON |BS_LEFT |WS_CHILD |WS_GROUP|WS_TABSTOP |WS_VISIBLE ,15,4,252,10
   CONTROL "precision 2",1151,"BUTTON",BS_AUTORADIOBUTTON |BS_LEFT |WS_CHILD | WS_VISIBLE ,15,33,252,10
   CONTROL "precision 3",1152,"BUTTON",BS_AUTORADIOBUTTON |BS_LEFT |WS_CHILD | WS_VISIBLE ,15,62,252,10
   CONTROL "info 1",1153,"STATIC",SS_LEFT |WS_CHILD |WS_VISIBLE ,28,17,245,8
@@ -169,29 +171,30 @@ EXSTYLE WS_EX_CONTROLPARENT
 CAPTION "tab5"
 FONT 8, "Ms Shell Dlg"
 BEGIN
-    COMBOBOX        1156,58,5,63,200,CBS_DROPDOWNLIST | WS_TABSTOP
+    COMBOBOX        1156,58,5,63,200,CBS_DROPDOWNLIST | WS_TABSTOP | WS_GROUP
     COMBOBOX        1157,58,19,63,200,CBS_DROPDOWNLIST | WS_TABSTOP
     LTEXT           "Input",1162,11,7,27,8
     LTEXT           "Output",1163,11,22,29,8
     LTEXT           "Rounding",1164,11,36,43,8
     COMBOBOX        1159,58,33,121,200,CBS_DROPDOWNLIST | WS_TABSTOP
-    CONTROL         "Always",1160,"Button",BS_AUTORADIOBUTTON | BS_LEFT | WS_TABSTOP,19,65,44,10
+    CONTROL         "Always",1160,"Button",BS_AUTORADIOBUTTON | BS_LEFT | WS_GROUP | WS_TABSTOP,19,65,44,10
     CONTROL         "When exp greater than:",1161,"Button", BS_AUTORADIOBUTTON | BS_LEFT ,77,65,112,10
-    EDITTEXT        1166,194,63,29,14,WS_TABSTOP | ES_NUMBER
+    EDITTEXT        1166,194,63,29,14,WS_GROUP | WS_TABSTOP | ES_NUMBER
     CONTROL         "",1165,"msctls_updown32",UDS_SETBUDDYINT | UDS_ALIGNRIGHT | UDS_ARROWKEYS ,213,37,11,14
     GROUPBOX        "Print scientific value",1168,11,51,240,31
     LTEXT           "Digit",1167,227,65,20,8
 END
 
-
-200 DIALOG 0, 0, 349, 202
-STYLE DS_SETFONT | DS_MODALFRAME | DS_CENTER | WS_POPUP | WS_VISIBLE | WS_CAPTION | WS_SYSMENU
+200 DIALOG DISCARDABLE  0, 0, 349, 202
+STYLE DS_MODALFRAME | DS_CENTER | WS_POPUP | WS_VISIBLE | WS_CAPTION | 
+    WS_SYSMENU
 CAPTION "About"
 FONT 8, "MS Sans Serif"
 BEGIN
-    CONTROL 1201,0,"Static",SS_BITMAP,3,3,101,197
-    EDITTEXT        1200,112,3,231,197,ES_MULTILINE | ES_READONLY | NOT 
+    CONTROL         1201,0,"Static",SS_BITMAP,3,3,101,197
+    EDITTEXT        1200,112,3,231,158,ES_MULTILINE | ES_READONLY | NOT 
                     WS_BORDER | NOT WS_TABSTOP
+    DEFPUSHBUTTON   "Close",IDOK,175,172,86,14
 END
 
 1201 BITMAP "..\\res\\abacus_01.bmp"
diff --git a/src/tabs.cpp b/src/tabs.cpp
index 4d7a4cc..955bfbe 100644
--- a/src/tabs.cpp
+++ b/src/tabs.cpp
@@ -315,16 +315,21 @@ return true;
 
 BOOL WmTabCommand_Ok(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
 {
-int tab = TabCtrl_GetCurSel(GetParent(hWnd));
+HWND main = GetPrgRes()->GetMainWindow();
+HWND tab  = GetDlgItem(main, IDC_TAB);
+int sel   = TabCtrl_GetCurSel(tab);
 
-	if( tab == tab_variables )
+
+	if( sel == tab_variables )
 	{
-		Variables::WmTabCommand_EditVariable(hWnd, WM_COMMAND, IDC_BUTTON_EDIT_VARIABLE, 0);
+		if( GetFocus() == GetDlgItem(GetPrgRes()->GetTabWindow(tab_variables), IDC_VARIABLES_LIST ) )
+			Variables::WmTabCommand_EditVariable(hWnd, WM_COMMAND, IDC_BUTTON_EDIT_VARIABLE, 0);
 	}
 	else
-	if( tab == tab_functions )
+	if( sel == tab_functions )
 	{
-		Functions::WmTabCommand_EditFunction(hWnd, WM_COMMAND, IDC_BUTTON_EDIT_FUNCTION, 0);
+		if( GetFocus() == GetDlgItem(GetPrgRes()->GetTabWindow(tab_functions), IDC_FUNCTIONS_LIST ) )
+			Functions::WmTabCommand_EditFunction(hWnd, WM_COMMAND, IDC_BUTTON_EDIT_FUNCTION, 0);
 	}
 
 return true;
@@ -726,26 +731,66 @@ BOOL WmTabInitDialog(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
 }
 
 
+/*!
+	this function enables or disables the 'edit' and 'delete' buttons
+	on the variables' or functions' tab depending on how many variables
+	are selected in the list
+*/
+void SetDisablingEditDeleteVariableOrFunctionButtons(int count, HWND add,
+													 HWND edit, HWND del, HWND focus)
+{
+	if( count == 1 )
+		// if there is one selected item we're enabling the edit button
+		EnableWindow(edit, true);
+	else
+	{
+		// if there is not one selected item (or none) we're disabling the edit
+		EnableWindow(edit, false);
+	
+		// if the focus is on the edit button we must change it 
+		// for example into the add button
+		// (we must change the BS_DEFPUSHBUTTON style as well)
+		if( focus == edit )
+		{
+			SetFocus(add);
+			SendMessage(add, BM_SETSTYLE, (WPARAM)BS_DEFPUSHBUTTON, true);
+			SendMessage(edit, BM_SETSTYLE, (WPARAM)BS_PUSHBUTTON, true);
+		}
+	}
+
+
+	if( count != 0 )
+		// if there is one or more items selected we're enabling the del button
+		EnableWindow(del, true);
+	else
+	{
+		// if there are not selected items we're disabling the del
+		EnableWindow(del, false);
+		
+		if( focus == del )
+		{
+			SetFocus(add);
+			SendMessage(add, BM_SETSTYLE, (WPARAM)BS_DEFPUSHBUTTON, true);
+			SendMessage(del, BM_SETSTYLE, (WPARAM)BS_PUSHBUTTON, true);
+		}
+	}
+}
+
+
 /*!
 	this function enables or disables the 'edit' and 'delete' buttons
 	on the variable's tab depending on how many variables are selected in the list
 */
 void SetDisablingEditDeleteVariableButtons(HWND hWnd)
 {
-HWND list = GetDlgItem(hWnd,IDC_VARIABLES_LIST);
+HWND focus = GetFocus();
+HWND list  = GetDlgItem(hWnd, IDC_VARIABLES_LIST);
+HWND add   = GetDlgItem(hWnd, IDC_BUTTON_ADD_VARIABLE);
+HWND edit  = GetDlgItem(hWnd, IDC_BUTTON_EDIT_VARIABLE);
+HWND del   = GetDlgItem(hWnd, IDC_BUTTON_DELETE_VARIABLE);
+int count  = ListView_GetSelectedCount(list);
 
-int count = ListView_GetSelectedCount(list);
-
-	if( count == 1 )
-		EnableWindow(GetDlgItem(hWnd, IDC_BUTTON_EDIT_VARIABLE), true);
-	else
-		EnableWindow(GetDlgItem(hWnd, IDC_BUTTON_EDIT_VARIABLE), false);
-
-
-	if( count != 0 )
-		EnableWindow(GetDlgItem(hWnd, IDC_BUTTON_DELETE_VARIABLE), true);
-	else
-		EnableWindow(GetDlgItem(hWnd, IDC_BUTTON_DELETE_VARIABLE), false);
+	SetDisablingEditDeleteVariableOrFunctionButtons(count, add, edit, del, focus);
 }
 
 
@@ -755,44 +800,44 @@ int count = ListView_GetSelectedCount(list);
 */
 void SetDisablingEditDeleteFunctionButtons(HWND hWnd)
 {
-HWND list = GetDlgItem(hWnd,IDC_FUNCTIONS_LIST);
+HWND focus = GetFocus();
+HWND list  = GetDlgItem(hWnd, IDC_FUNCTIONS_LIST);
+HWND add   = GetDlgItem(hWnd, IDC_BUTTON_ADD_FUNCTION);
+HWND edit  = GetDlgItem(hWnd, IDC_BUTTON_EDIT_FUNCTION);
+HWND del   = GetDlgItem(hWnd, IDC_BUTTON_DELETE_FUNCTION);
+int count  = ListView_GetSelectedCount(list);
 
-int count = ListView_GetSelectedCount(list);
-
-	if( count == 1 )
-		EnableWindow(GetDlgItem(hWnd, IDC_BUTTON_EDIT_FUNCTION), true);
-	else
-		EnableWindow(GetDlgItem(hWnd, IDC_BUTTON_EDIT_FUNCTION), false);
-
-
-	if( count != 0 )
-		EnableWindow(GetDlgItem(hWnd, IDC_BUTTON_DELETE_FUNCTION), true);
-	else
-		EnableWindow(GetDlgItem(hWnd, IDC_BUTTON_DELETE_FUNCTION), false);
+	SetDisablingEditDeleteVariableOrFunctionButtons(count, add, edit, del, focus);
 }
 
 
-void FillUpVariableList(HWND list)
+int FillUpVariableList(HWND list)
 {
 	// we don't have to block the second thread here
 	// because it can only read from variables' table
 	// (we can read and the second thread can read in the same time as well)
 	ttmath::Objects::CIterator iv = GetPrgRes()->GetVariables()->Begin();
 
-	for( ; iv != GetPrgRes()->GetVariables()->End() ; ++iv )
+	int size;
+	for( size=0 ; iv != GetPrgRes()->GetVariables()->End() ; ++iv, ++size )
 		Variables::AddNewItemToVariableList(list, iv->first, iv->second.value);
+
+return size;
 }
 
 
-void FillUpFunctionList(HWND list)
+int FillUpFunctionList(HWND list)
 {
 	// we don't have to block the second thread here
 	// because it can only read from functions' table
 	// (we can read and the second thread can read in the same time as well)
 	ttmath::Objects::CIterator iv = GetPrgRes()->GetFunctions()->Begin();
 
-	for( ; iv != GetPrgRes()->GetFunctions()->End() ; ++iv )
+	int size;
+	for( size=0 ; iv != GetPrgRes()->GetFunctions()->End() ; ++iv, ++size )
 		Functions::AddNewItemToFunctionList(list, iv->first, iv->second.value, iv->second.param);
+
+return size;
 }
 
 
@@ -814,9 +859,10 @@ LVCOLUMN column;
 	ListView_InsertColumn(list, 1, &column);
 
 	ListView_SetExtendedListViewStyle(list,LVS_EX_FULLROWSELECT);
-
 	SetDisablingEditDeleteVariableButtons(hWnd);
-	FillUpVariableList(list);
+
+	if( FillUpVariableList(list) > 0 )
+		ListView_SetItemState(list, 0, LVIS_SELECTED, LVIS_SELECTED);
 
 return true;
 }
@@ -845,7 +891,10 @@ LVCOLUMN column;
 	ListView_SetExtendedListViewStyle(list,LVS_EX_FULLROWSELECT);
 
 	SetDisablingEditDeleteFunctionButtons(hWnd);
-	FillUpFunctionList(list);
+
+	if( FillUpFunctionList(list) > 0 )
+		ListView_SetItemState(list, 0, LVIS_SELECTED, LVIS_SELECTED);
+	
 
 return true;
 }
@@ -957,6 +1006,16 @@ return false;
 }
 
 
+BOOL WmTabKeyDown(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
+{
+MessageBox(hWnd, "trol", "", 0);
+
+return true;
+
+
+}
+
+
 void CreateTabMessagesTable(Messages & messages)
 {
 	messages.Associate(WM_INITDIALOG,			WmTabInitDialog);
@@ -966,6 +1025,7 @@ void CreateTabMessagesTable(Messages & messages)
 	messages.Associate(WM_INIT_TAB_PRECISION,	WmInitTabPrecision);
 	messages.Associate(WM_INIT_TAB_DISPLAY,		WmInitTabDisplay);
 	messages.Associate(WM_NOTIFY,				WmNotify);
+	messages.Associate(WM_KEYDOWN,				WmTabKeyDown);
 }
 
 
@@ -1024,7 +1084,7 @@ RECT r_main, r;
 		sum += ListView_GetColumnWidth(list, i);
 
 	if( sum < list_cx - 30 )
-		ListView_SetColumnWidth(list, last_column, list_cx-sum-10);
+		ListView_SetColumnWidth(list, last_column, list_cx-sum-25);
 }
 
 
diff --git a/src/tabs.h b/src/tabs.h
index 9e93e9c..3626cb9 100644
--- a/src/tabs.h
+++ b/src/tabs.h
@@ -73,6 +73,7 @@ extern ttmath::ErrorCode last_code;
 	void SetLanguage(HWND hTab);
 	void SetSizeOfVariablesList();
 	void SetSizeOfFunctionsList();
+	BOOL WmTabCommand(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
 
 	namespace Variables
 	{
diff --git a/src/variables.cpp b/src/variables.cpp
index 7163316..ef471c4 100644
--- a/src/variables.cpp
+++ b/src/variables.cpp
@@ -100,7 +100,7 @@ char * pchar;
 		}
 		else
 		{
-			EnableWindow(GetDlgItem(hWnd,IDC_EDIT_VARIABLE_NAME), false);
+			SendDlgItemMessage(hWnd, IDC_EDIT_VARIABLE_NAME, EM_SETREADONLY, 1, 0);
 			SetFocus(GetDlgItem(hWnd,IDC_EDIT_VARIABLE_VALUE));
 		}
 
@@ -204,12 +204,13 @@ const char * message;
 
 
 
-BOOL WmTabCommand_AddVariable(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
+BOOL WmTabCommand_AddVariable(HWND, UINT message, WPARAM wParam, LPARAM lParam)
 {
-	caption = GetPrgRes()->GetLanguages()->GuiMessage(Languages::dialog_box_add_variable_caption);
-	name    = "";
-	value   = "";
-	adding  = true;
+	HWND hWnd = GetPrgRes()->GetTabWindow(TabWindowFunctions::tab_variables);
+	caption   = GetPrgRes()->GetLanguages()->GuiMessage(Languages::dialog_box_add_variable_caption);
+	name      = "";
+	value     = "";
+	adding    = true;
 
 	if( DialogBox(GetPrgRes()->GetInstance(), MAKEINTRESOURCE(IDD_DIALOG_ADD_VARIABLE), hWnd, DialogProcVariables) )
 	{
@@ -235,8 +236,9 @@ return true;
 	(we're also using this method directly without using the main loop of messages)
 	(we don't define the 'lParam' parameter there)
 */
-BOOL WmTabCommand_EditVariable(HWND hWnd, UINT message, WPARAM wParam, LPARAM)
+BOOL WmTabCommand_EditVariable(HWND, UINT message, WPARAM wParam, LPARAM)
 {
+HWND hWnd = GetPrgRes()->GetTabWindow(TabWindowFunctions::tab_variables);
 HWND list = GetDlgItem(hWnd, IDC_VARIABLES_LIST);
 
 	if( ListView_GetSelectedCount(list) != 1 )
@@ -269,8 +271,9 @@ return true;
 }
 
 
-BOOL WmTabCommand_DeleteVariable(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
+BOOL WmTabCommand_DeleteVariable(HWND, UINT message, WPARAM wParam, LPARAM lParam)
 {
+HWND hWnd = GetPrgRes()->GetTabWindow(TabWindowFunctions::tab_variables);
 HWND list = GetDlgItem(hWnd, IDC_VARIABLES_LIST);
 int items = ListView_GetSelectedCount(list);
 
diff --git a/src/winmain.cpp b/src/winmain.cpp
index 17e07c9..efe57d9 100644
--- a/src/winmain.cpp
+++ b/src/winmain.cpp
@@ -117,12 +117,20 @@ MSG msg;
 	{
 		bool sended = false;
 
-		if( msg.message==WM_KEYDOWN && msg.wParam==VK_TAB )
+		// we give our own special function for navigating from the keyboard
+		// if our function returns false then we use a standard navigation
+		// from the system
+		if( msg.message == WM_KEYDOWN &&
+		  ( msg.wParam == VK_TAB  || 
+		    msg.wParam == VK_DOWN || msg.wParam == VK_UP  ||
+		    msg.wParam == VK_LEFT || msg.wParam == VK_DOWN  ) )
+
 		{	
-			MainWindowFunctions::SetNextFocus();
-			sended = true;
+			if( MainWindowFunctions::SetNextFocus(msg.wParam) )
+				sended = true;
 		}
 
+
 		// firt we try to send our message to dialogs
 		// (the dialogs on the tab control)
 		if( !sended )
diff --git a/src/winmain.h b/src/winmain.h
index 740ddfb..69fcaff 100644
--- a/src/winmain.h
+++ b/src/winmain.h
@@ -63,7 +63,7 @@ void MainMessagesLoop();
 
 namespace MainWindowFunctions
 {
-	void SetNextFocus();
+	bool SetNextFocus(WPARAM wParam);
 	void CreateMainMessagesTable(Messages & messages);
 	BOOL CALLBACK AboutProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
 }