Cannot scroll in editor

Since the last one or two weeks I stumbled upon the problem that I sometimes cannot use the scroll bar in the editor view. Scrolling using the mouse wheel works as expected. However, I cannot grab the scroll bar and move it up or down. Scrolling in other views/panes (e.g. "Compile Output") works as normal.

May it be an issue with the messages generated by the clang backend? These messages are indicated as colored bars above (!!) the scroll bar.

I am using Antergos Linux. The output of qtdiag is attached in file scroll_bug_qtdiag.txt.