The Delphi Bug List

This can be tested with the following:

• Create a new application, create main menu and add some menu items.
• Insert TStatusBar and create in this status bar two or more panels and set TStatusBar.SimplePanel := False.
• Select some of status bar panels and set for each of these status panels Style := psOwnerDraw.
• Run this application and you will be surprised to see the main menu items drawn in the status bar panels (starting from Panels[1]).

This can be reproduced only under Windows NT 4.0. Same application running on a Windows 98 machine do not expose such behaviour.

This seems to be a TStatusBar bug, but actually this bug is coming from incorrect message handling in Forms.pas:

procedure TCustomForm.WndProc(var Message: TMessage);
...
      WM_DRAWITEM:
        with PDrawItemStruct(Message.LParam)^ do
          if (CtlType = ODT_MENU) and Assigned(Menu) then
          begin
            { here is main menu drawing }
          end;

      WM_DRAWITEM:
        if Message.WParam = 0 then
        with PDrawItemStruct(Message.LParam)^ do
          if (CtlType = ODT_MENU) and Assigned(Menu) then
          begin
            { here is main menu drawing }
          end;

But for this solution forms.pas must be modified.

The workaround itself:
When implementing owner-drawn status panels the following code can be used in form unit containing custom-drawn status bar:

TForm1=class(TForm)
 ...
  protected
    procedure WndProc(var Message: TMessage); override;
 ...

procedure TForm1.WndProc(var Message: TMessage);
begin
  if (Message.Msg = wm_DrawItem) and
     (Message.WParam <> 0) and
     (Message.LParam <> 0) then
    with PDrawItemStruct(Message.LParam)^ do
      if (CtlType = ODT_MENU) then
     CtlType := 0;
  inherited;
end;

Parameter CtlType is not used when Windows notifies with WM_DRAWITEM for status panels, but under WinNT4.0 this parameter is equal to ODT_MENU (1) and menu item is drawn inside of status panel rectangle.

Note from checker:
On my NT 4.0 (SP6) system, WParam was 0, not ODT_MENU. I suppose the version of COMCTL32.DLL probably determines whether this bug appears.

Very quick fix - put the status bar on a Panel not directly on the form. I reported this to Borland last February (2000)
jeff