[COMCTL32] Comboboxes v6 with many elements do auto-close erroneously with low vertical resolution when clicking on the text

a splitoff from CORE-18665 covering the comctl32-part:

Reproduction steps

• set a very low screen resolution, e.g. 640x480 to limit available vertical space
• the attached timedate_unlimited.cpl uses a v6 combobox that does not explicitly limit the amount of elements in its timezone combobox yet, and therefore will show 30 elements by default
• 30 elements are so many, that the expanded box would not fit all of them to the screen in 640x480, neither when expanding the combobox to the bottom, nor when it expands the combobox to the top
• place the dialog in the vertical center of the screen
• open the v6 combobox with a single click on its text, not a click on the small triangle to the right

Expected result
2k3sp2 would still show the combobox in expanded state when the mouse button is released 2k3sp2_ok.png

Observed result
On ros with comctl32 v6 combobox from Wine the combobox will expand on the click as intended,
but the release of the mouse button will already do the selection and therefore the bx auto-closes immediately again unintentionally.
ROS_0.4.15-dev-5402-gf908d37_affected.webm

We do believe this to be a bug in Wines comctl32 v6.

Reminder

• Use only the timedate_unlimited.cpl attached here for testing, not the one from master, as it got a workaround already)