Problems with taskbar at top of screen

I have moved my taskbar to the top of my screen but sometimes when
applications open, they open with the top of their windows hidden behind the
taskbar because their window is aligned to the top of the screen also, sort
of like it is not recognizing that the taskbar is/could be at the top. In
order to bring the window down so that it is not covered by the taskbar, I
have to unlock the task bar (which I then relock but the unlocking is enough
to bring the window down). I have tried to have the taskbar unlocked and
the problem still exists and is worked around by locking the taskbar. It
seems to be a bug but I don't know if it is a bug in Windows or the
applications....any ideas?

This issue almost exists on very version of Winodws.
I think it's not a bug, but a lack of feature. Because Windows allows applications to determine their size and positions by themselves, and that is exactly a feature.

One solution is making the taskbar under applications by unchecking Taskbar Always On Top in the properties of the taskbar.
Or use a third party tool Titlebar Guard.