I'm very annoyed by the current pan behavior:
it doesn't let move the canvas around enough !

I mean with a zoom level set to fit page, you can't pan it at all.
What if I want the top-left corner of the canvas on the right-bottom corner of the screen to draw on it ?!

It would be much more handy to can pan "infinitely" the canvas (or at least have much more space to pan).

Yes, that's right. It's https://bugs.kde.org/show_bug.cgi?id=189541 in bugzilla.

Ok, I hope you'll reach to fix this one then.

This is fixed, great!