Using AHK's WindowSpy tool:
When the mousePointer is within the top half of the panel1) Activate TC's QuickView.
2) Put cursor on a non-graphical file, i.e. [..] or a [Folder], .zip or .txt, etc.
3) Hover the mouse on the QuickView panel, and note the ClassNN value:
the class is noted as: TMyTabControl1 (Left Panel)
When the mousePointer is within the bottom half of the panel
the class is noted as: TLister1 (Left Panel)
I cannot reproduce this using something like WinSpector, but WinSpector doesn't seem to return real values in it's "QuickInfo" Class box. Since WinSpector indicates the class is TLister for the whole QuickView panel, and it should be TLister1. Similarly WinSpector will report the class of the File panels as TMyListBox and not indicate 1 or 2 where necessary.
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Likewise, WinSpector reports both of TC's Left|Right Tabs are TMyTabControl no matter where the mouse pointer is situated over any open Tabs.
Whereas, WindowSpy reports without any apparent consistent pattern, when moving the mouse over the Tabs:
(Left Tabs ) TMyPanel4 and TMyTabControl1
(RightTabs) TMyPanel7 and TMyTabControl2
I've also not seen this misbehaviour (of class reporting) of WindowSpy in any other applications before.