Add a slider tool that when slid to the left rotates the image towards the left. When slid to the right, rotates the image to the right. Reproducible: Always
We have keyboard shortcuts for that and are working on a widget to show the rotation as a canvas overlay. I don't think that having a slider that is always visible is a what we want here.
A slider is not very user friendly and a bit limited IMHO. I suggest to add an optional ever present "compass" or disc overlay to the overview docker. The compass would have a triangle showing document's north. To rotate. press and drag the disc. Left to rotate left, right to rotate right.
That, but on the canvas itself instead, is something Arjen has been working on already.
WISHGROUP: Small Usability Fixes
This has been implemented in the popup palette.