If the taskbar is set to auto-hide then the full window space excluding any appbars (docked windows) is what the skin is meant to use so the taskbar will then just pop-up over it when needed.
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-dro
It appears to depend on the skin. Some of the modern skins in my collection (or panels within them) cover the whole screen when the taskbar is set to auto-hide and the taskbar doesn't pop-up then pointing to the bottom edge of the screen (where the taskbar is docked). Sometimes, depending on the skin panel that is maximized, a few pixels across the bottom of the screen are not covered. In these cases, pointing to this area does cause the taskbar to pop-up over the skin.
For example, the Komodo X Touchscreen v1.0 by Victhor has 7 panels that can each be maximized. The media library and video panels leave the pixels at the bottom of the screen uncovered when they are maximized. The other 5 panels cover the whole screen and thus prevent being able to make the taskbar pop-up.
As I stated in my earlier post, this behavior is not an issue for me. I like having a maximized skin cover as much of my screen as possible.
I usually return a maximized skin to normal size before switching to another skin. Two days ago (Aug 5th) I managed to make WACUP crash when switching from a maximized modern skin to another modern skin. Today I did virtually the same thing and WACUP didn't crash. I think the crash report was sent. If not and you want to see it, I can PM it to you.