TLabel displays accelerator keys even when the UI state says not to

Question

With default Windows settings, accelerator keys are not meant to be shown on dialogs until the user presses the ALT key.

Delphi\'s TLabel control

Answer 1

I think I've worked out a way of handling it.

function HideAccelFlag(Control: TControl): Integer;
begin
  //ask the top level window about its UI state
  while Assigned(Control.Parent) do begin
    Control := Control.Parent;
  end;
  if (Control.Perform(WM_QUERYUISTATE, 0, 0) and UISF_HIDEACCEL)=UISF_HIDEACCEL then begin
    Result := DT_HIDEPREFIX;
  end else begin
    Result := 0;
  end;
end;

type
  TUIStateAwareLabel = class(TLabel)
  protected
    procedure DoDrawText(var Rect: TRect; Flags: Longint); override;
  end;

procedure TUIStateAwareLabel.DoDrawText(var Rect: TRect; Flags: Integer);
begin
  if ShowAccelChar then begin
    Flags := Flags or HideAccelFlag(Self);
  end;
  inherited;
end;

I make sure that I always create TUIStateAwareLabel rather than TLabel by hooking the form streaming mechanism with TReader.OnFindComponentClass.

Dealing with TCustomGroupBox descendents is more messy. For them I resorted to copying the source code of TCustomGroupBox.Paint into my descendent and making use of HideAccelFlag again.

Next task is to write it up as a QC report.