With all these new buttons (DragMath and NanoGong), my toolbar is leaving the editor box, you see it also here on moodle.org (see screendump)
By two little changes, I have them back in the box:
line 17 in /lib/editor/htmlarea/htmlarea.css (toolbar button)
was: padding: 1px;
now: padding: .1px;
line 26 in /lib/editor/htmlarea/htmlarea.css (toolbar buttonactive)
was: padding: 2px 0px 0px 2px;
now: padding: .1px 0px 0px 2px;