Generic Solution to Coloring the Focused Entry Control

RTTI to the Rescue!

The implementation of the Screen's OnActiveControlChange event handler calls the custom "EnterColor" procedure for the currently focused data entry control after a call to "ExitColor" for the previuosly selected one:

procedure TMainForm.EnterColor(Sender: TWinControl) ;
begin
   if Sender <> nil then
   begin
     if IsPublishedProp(Sender,'Color') then
     begin
       originalColor := GetOrdProp(Sender,'Color') ;
       SetOrdProp(Sender,'Color', focusColor) ;
     end;
   end;
end;

First you make sure that the "Color" property is exposed by "Sender" using the "IsPublishedProp" procedure. Next, you store the original background color value using the "GetOrdProp" procedure. Finally, the "SetOrdProp" changes the background color to the color we specified to be used for focused controls.

You also need to make sure that the control that had focus has its background color restored:

procedure TMainForm.ExitColor(Sender: TWinControl) ;
begin
   if Sender <> nil then
   begin
     if IsPublishedProp(Sender,'Color') then
     begin
       SetOrdProp(Sender,'Color',originalColor) ;
     end;
   end;
end;

Make sure you download the full source code.

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