TTabSheet hints in Delphi

delphi, tooltip, ttabsheet

Solution

Just hook the Page Control's Mouse Move event and use the TabAtPos property to determine which tab the mouse is hovering over. Then assign that tab's Hint to the Page Control's hint property.

procedure TForm.PageMouseMove(Sender: TObject; Shift: TShiftState; X, Y: integer);
var
  tabindex: integer;
begin
  tabindex := PageControl.IndexOfTabAt(X, Y);
  if (tabindex >= 0) and (PageControl.Hint <> PageControl.Pages[tabindex].Hint) then
  begin
    Application.CancelHint;
    PageControl.Hint := PageControl.Pages[tabindex].Hint;
    PageControl.ShowHint := true;
  end;
end;

CancelHint/ShowHint will take care of updating the hint window when mouse moves directly from one tab to another.

Improved but ugly version below also temporarily changes HintPause to 0 when mouse is moved directly from tab to tab so that the hint is redisplayed immediately. (The "ugly" part of the solution goes to the Application.ProcessMessages call which forces hint messages to be processed before HintPause is restored.)

procedure TForm.PagesMouseMove(Sender: TObject; Shift: TShiftState; X, Y: integer);
var
  hintPause: integer;
  tabindex: integer;
begin
  tabindex := PageControl.IndexOfTabAt(X, Y);
  if (tabindex >= 0) and (PageControl.Hint <> PageControl.Pages[tabindex].Hint) then
  begin
    hintPause := Application.HintPause;
    try
      if PageControl.Hint <> '' then
        Application.HintPause := 0;
      Application.CancelHint;
      PageControl.Hint := PageControl.Pages[tabindex].Hint;
      PageControl.ShowHint := true;
      Application.ProcessMessages; // force hint to appear
    finally Application.HintPause := hintPause; end;
  end;
end;

To hide the hint on the main page body, assign the following method to the page control's OnMouseLeave event.

procedure TForm.PageMouseLeave(Sender: TObject);
begin
  PageControl.Hint := '';
  PageControl.ShowHint := false;
end;

Problem

Original source