Clicking to the left (resp. right) or RTL text puts the caret to the right (resp. left) of the text. The caret should be positioned at the edge of the text which is closer to the click position. See the attached test case.
Created attachment 7484 [details]
this is also reproducible with contenteditable divs.
I'm pretty sure the problem is in RenderText::positionForCoordinates
I have a fix for this... just working on a test now.
Verified in r13271 nightly. I think this fix is even more important for Mail!