krita 4.1.7.101 & qt 5.12

[Harald Sitter]

Salut distros!

This is a quick reminder that Krita 4.1.7.101 is not properly tested
on Qt 5.12 and you should ideally not mix the two.

If you absolutely must land 5.12 I'd advise that you at least pick up
this patchy here [1] and build with USE_QT_XCB=ON.

A main problem is that krita has internal xcb magic which conflicts
with Qt 5.12's reworked xcb platform plugin to the point where all
mouse input is simply ignored. Switching to Qt's built-in xcb solves
this problem but may cause krita to hang when using a tablet. It's
unclear if the hanging defect is still applicable to 5.12 at this
time.

There may be other problems that we are as-yet unaware of, so, be
mindful of that.

[1] https://packaging.neon.kde.org/extras/krita.git/plain/debian/patches/0001-Add-a-cmake-option-to-disable-our-own-tablet-support.patch?h=Neon/release&id=dda9ab62ea2e0c41395e2834395fd49fdc91132a

HS