System Menu for Layered Windows?

Question

We're having an issue with layered windows and system menus in Delphi 2009. That is, our layered windows (which have no border) have no system menu. When I say system menu, I am referring to the menu you get when clicking an application's icon, right clicking it's title-bar or (in Windows 7, with the addition of the shift key,) right clicking an application in the task-bar:

When you attempt to access the system menu, e.g. by right-clicking on the task-bar icon, of such a layered window, instead the layered window is risen. Why is this? Is there some sort of style to set, or some sort of event to handle?

Here's a hastily made demo showing the issue. It can really be reproduced with any form with a bsNone borderstyle, though.

http://ompldr.org/vODd5dw

Answer 1

You need to add back the WS_SYSMENU style which is removed with bsNone border style.

type
  TLayeredForm = class(TForm)
    procedure FormCreate(Sender: TObject);
  protected
    procedure CreateParams(var Params: TCreateParams); override;
  end;

...

procedure TLayeredForm.CreateParams(var Params: TCreateParams);
begin
  inherited;
  Params.Style := Params.Style or WS_SYSMENU;
end;