2.79 texture paint issue

I’m using MacOS High Sierra 10.13.6. And atm I have an issue with texture painting.
Experimental biuld.
Date: 2019-02-15 07:56
Hash: 9800837b9879
Branch: blender 2.7
First of all, preview window doesn’t show my current texture to paint.
Second, Cmd+z (ctrl+z) crashes Blender

Crashes should be reported to the bug tracker!

actually it goes to an endless freeze. How can I report in this case? moreover -as u can see on the screen - there is a prob;em with texture viewport - nothing shows there. ty

As I said, such matters are left for the bug tracker.