Hello
If you going to extend standard filter form - TDBGridFilterDropDownForm
You can inherit TDBGridFilterDropDownForm and
Code:
TNewFilterForm = class(TDBGridFilterDropDownForm)
...
assign global variable DBGridFilterDropDownForm
Code:
initialization
DBGridFilterDropDownForm := TNewFilterForm.Create(Application);
end.
If you are going to write new filter form from scratch.
You should change source code of DBGridEh.pas
procedure TCustomDBGridEh.InTitleFilterDropDownFormForRect(Column: TColumnEh; ForRect: TRect);
You can copy DBGridEh.pas to the folder with your project and change
TCustomDBGridEh.InTitleFilterDropDownFormForRect
method