Author: Jonas Bilinkevicius

I have a PageControl having 3 TabSheets. If this PageControl has a Panel as its 
parent, then I am able navigate between the tabsheets using Ctrl-Tab (forward) or 
Shift-Ctrl-Tab (backward) using the keyboard. But if the same pagecontrol has 
another Tabsheet of a Pagecontrol as its parent, then I am not able to navigate 
between the tabsheets of the child pagecontrol using the keyboard even though the 
focus is on the child pagecontrol.

Answer:

Handling proper Ctrl-Tab and Ctrl-Shift-Tab switching of pages if several 
pagecontrols are on a form:

In form declaration:
1   
2   procedure CMDialogKey(var msg: TCMDialogKey); message CM_DIALOGKEY;
3   
4   procedure TForm1.CMDialogKey(var msg: TCMDialogKey);
5   var
6     Control: TWinControl;
7   begin
8     with Msg do
9     begin
10      if (charcode = VK_TAB) and (GetKeyState(VK_CONTROL) < 0) then
11      begin
12        Control := ActiveControl;
13        while Assigned(Control) do
14          if Control is TPageControl then
15          begin
16            Control.Perform(CM_DIALOGKEY, charcode, keydata);
17            Exit;
18          end
19          else
20            Control := Control.Parent;
21      end;
22    end;
23    inherited;
24  end;