diff --git a/src/functions.cpp b/src/functions.cpp
index 3c40ca4..e7c01ac 100644
--- a/src/functions.cpp
+++ b/src/functions.cpp
@@ -275,7 +275,7 @@ return true;
 }
 
 
-BOOL WmTabCommand_DeleteFunction(HWND, UINT message, WPARAM wParam, LPARAM lParam)
+BOOL WmTabCommand_DeleteFunction(HWND, UINT, WPARAM, LPARAM)
 {
 HWND hWnd = GetPrgRes()->GetTabWindow(TabWindowFunctions::tab_functions);
 HWND list = GetDlgItem(hWnd, IDC_FUNCTIONS_LIST);
diff --git a/src/languages.cpp b/src/languages.cpp
index 45e73b1..6a50be8 100644
--- a/src/languages.cpp
+++ b/src/languages.cpp
@@ -95,6 +95,7 @@ void Languages::InitErrorMessagesTab()
 	InsertErrorPair(ttmath::err_interrupt,"?");
 	InsertErrorPair(ttmath::err_overflow,"Overflow");
 	InsertErrorPair(ttmath::err_unknown_function,"An unknown function");
+	InsertErrorPair(ttmath::err_unknown_operator,"An unknown operator");
 	InsertErrorPair(ttmath::err_unexpected_semicolon_operator,"An unexpected semicolon operator");
 	InsertErrorPair(ttmath::err_improper_amount_of_arguments,"Improper amount of arguments");
 	InsertErrorPair(ttmath::err_improper_argument,"Improper argument");
@@ -124,6 +125,7 @@ void Languages::InitErrorMessagesTab()
 	InsertErrorPair(ttmath::err_interrupt,"?");
 	InsertErrorPair(ttmath::err_overflow,"Przekroczony zakres");
 	InsertErrorPair(ttmath::err_unknown_function,"Nieznana funkcja");
+	InsertErrorPair(ttmath::err_unknown_operator,"Nieznany operator");
 	InsertErrorPair(ttmath::err_unexpected_semicolon_operator,"Nieoczekiwany operator 'średnik'");
 	InsertErrorPair(ttmath::err_improper_amount_of_arguments,"Niewłaściwa liczba argumentów");
 	InsertErrorPair(ttmath::err_improper_argument,"Niewłaściwy argument");
@@ -199,13 +201,13 @@ void Languages::InitGuiMessagesTab()
 	InsertGuiPair(dialog_box_add_variable_incorrect_value,"An incorrect value of the variable");
 	InsertGuiPair(dialog_box_add_variable_variable_exists,"This variable already exists");
 	InsertGuiPair(dialog_box_edit_variable_unknown_variable,"There isn't this variable in my table. There's probably an internal error!");
-	InsertGuiPair(dialog_box_delete_variable_confirm,"Are you sure that you want to delete those variables?");
+	InsertGuiPair(dialog_box_delete_variable_confirm,"Are you sure that you want to delete these variables?");
 	InsertGuiPair(dialog_box_variable_not_all_deleted,"There are some variables which I was not able to delete. Probably an internal error!");
 	InsertGuiPair(dialog_box_add_function_caption,"Add a new function");
 	InsertGuiPair(dialog_box_edit_function_caption,"Edit a function");
 	InsertGuiPair(dialog_box_add_function_function_exists,"This function already exists");
 	InsertGuiPair(dialog_box_edit_function_unknown_function,"There isn't this function in my table. There's probably an internal error!");
-	InsertGuiPair(dialog_box_delete_function_confirm,"Are you sure that you want to delete those functions?");
+	InsertGuiPair(dialog_box_delete_function_confirm,"Are you sure that you want to delete these functions?");
 	InsertGuiPair(dialog_box_function_not_all_deleted,"There are some functions which I was not able to delete. Probably an internal error!");
 	InsertGuiPair(dialog_box_add_function_incorrect_name,"An incorrect name of the function");
 
diff --git a/src/tabs.cpp b/src/tabs.cpp
index 955bfbe..b310a47 100644
--- a/src/tabs.cpp
+++ b/src/tabs.cpp
@@ -336,7 +336,6 @@ return true;
 }
 
 
-
 void SetLanguageTabStandard(HWND hWnd)
 {
 	SetDlgItemText( hWnd,IDC_BUTTON_CLEAR, GetPrgRes()->GetLanguages()->GuiMessage(Languages::button_clear) );
@@ -966,6 +965,7 @@ return true;
 }
 
 
+
 BOOL WmNotify(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
 {
 NMHDR * pnmh = (LPNMHDR) lParam;
@@ -979,12 +979,20 @@ HWND fun_list = GetDlgItem(hWnd,IDC_FUNCTIONS_LIST);
 			SetDisablingEditDeleteVariableButtons( hWnd );
 			return true;
 		}
-
+		else
 		if( pnmh->code == UINT(NM_DBLCLK) )
 		{
 			Variables::WmTabCommand_EditVariable(hWnd, WM_COMMAND, IDC_BUTTON_EDIT_VARIABLE, 0);	
 			return true;
 		}
+		else
+		if( pnmh->code == LVN_KEYDOWN )
+		{
+			NMLVKEYDOWN * pnkd = (NMLVKEYDOWN*) lParam;
+			
+			if( pnkd->wVKey == VK_DELETE )
+				Variables::WmTabCommand_DeleteVariable(0,0,0,0);
+		}
 	}
 
 	if( pnmh->hwndFrom == fun_list )
@@ -994,12 +1002,21 @@ HWND fun_list = GetDlgItem(hWnd,IDC_FUNCTIONS_LIST);
 			SetDisablingEditDeleteFunctionButtons( hWnd );
 			return true;
 		}
-
+		else
 		if( pnmh->code == UINT(NM_DBLCLK) )
 		{
 			Functions::WmTabCommand_EditFunction(hWnd, WM_COMMAND, IDC_BUTTON_EDIT_FUNCTION, 0);
 			return true;
 		}
+		else
+		if( pnmh->code == LVN_KEYDOWN )
+		{
+			NMLVKEYDOWN * pnkd = (NMLVKEYDOWN*) lParam;
+			
+			if( pnkd->wVKey == VK_DELETE )
+				Functions::WmTabCommand_DeleteFunction(0,0,0,0);
+		}
+
 	}
 
 return false;
diff --git a/src/variables.cpp b/src/variables.cpp
index ef471c4..da5979d 100644
--- a/src/variables.cpp
+++ b/src/variables.cpp
@@ -271,7 +271,7 @@ return true;
 }
 
 
-BOOL WmTabCommand_DeleteVariable(HWND, UINT message, WPARAM wParam, LPARAM lParam)
+BOOL WmTabCommand_DeleteVariable(HWND, UINT, WPARAM, LPARAM)
 {
 HWND hWnd = GetPrgRes()->GetTabWindow(TabWindowFunctions::tab_variables);
 HWND list = GetDlgItem(hWnd, IDC_VARIABLES_LIST);