TabControl and grouped OptionButtons

I like to put several OptionButton groups on a TabControl/TabControlPage.
To build groups of OptionButtons, I have to place them on frames.

If I don't group my OptionButtons, then it looks fine, but it doesn't work correct.
If I group my OptionButtons by placing them on non-visible Frames, there's a color problem.
Left side: without frames. Right side with frames.

What am I doing wrong? How does this work?

Remark: The frames of my samples are not invisible, I just set the BorderStyle property to 0=none.

Even if I use a PictureBox, it doesn't look good. Look at the new screenshot.

SourceCode:
Private Sub Form_Load()
   TabControl1.Color = xtpTabColorWinXP

   SkinFramework1.ApplyWindow Me.hWnd
   SkinFramework1.ApplyOptions = SkinFramework1.ApplyOptions Or xtpSkinApplyMetrics
   SkinFramework1.LoadSkin App.Path & "\WinXP.Luna.cjstyles", "Normalblue.ini"
End Sub

Visible Frames are very important to group the controls on a TabControlPage. Look at the Windows 2000 folder options screenshot above.
And it doesen't makes a difference if the frame is visual or not. The OptionButtons on the Frame on the TabControlPage on the TabControl are not drawn correct!

In the sample SkinMDISample on frmProperties I looks like it works. But there's a cheat: The OptionButtons are drawn on the TabControlPage itself and not on the frame. With this method you can not have multiple independent OptionButton groups on one TabControlPage.