Hmm... well I wrote a small test case on Windows. For me on WinNT, GetSystemMetrics(SM_CYCAPTION) returns 19 (which is also what Wine returns for me), while the initial trackbar thumb size is 21. On Win2k, GetSystemMetrics(SM_CYCAPTION) returns 20, but the the initial thumb size is still 21. So am I doing something wrong? It does not appear to me that the trackbar thumb size is related to SM_CYCAPTION.
By the way, for me, changing to [Version] "Windows" = "win2k"
still returns 19 for SM_CYCAPTION for me on Wine. I am assuming that should return 20?
I imagine the result on XP even depends on whether you are using the "new style" or "old style" window title bars.
Maybe not though.
Kelly