Instant freeze when dragging any icon for a file or folder in the browser i.e when pasting from file, under version 17.08.3 in Debian Buster/Sid + KDE Plasma 5.12.4 / Frameworks 5.44.0
you run kolourpaint inside a KDE plasma session ? And you mean you open a file dialog e.g. "pasting from file" and you then drag a file from this file dialog to kolourpaint, you see a freeze ? I could reproduce a short period of freezing when run kolourpaint within an xfce session on debian - although this must be some system setup thingy - does not come from kolourpaint itself.
*** This bug has been marked as a duplicate of bug 387039 ***