With 0.8.0 and 0.8.1 I experience text "flickery" (visual distortion) in kate with "x264" encoding and min-quality < 70.
With several paragraphs of text in kate all text is flashing in the rhythm of cursor flashing. Setting min-quality to 70 is enough to fix the problem.
70 is the minimum quality level for YUV422, below that you would be using YUV420 colour subsampling.
What is strange is that you get a full window refresh with just a cursor change. I guess that kate is updating the whole line or something, so we end up with a full window refresh rather than a small lossless (png/rgb24) region. Will test.
Just tested and I managed to reproduce the flickering issue in Kate. That's because the Kate application re-paints the whole line (or more?) every time the cursor blinks - so xpra does a full window refresh using x264. Then shortly after the auto-refresh kicks in and does a lossless refresh at high quality. The flickering is due to the difference in quality between regular frames and almost-lossless frames.
I'm trying to find out why the quality isn't higher on "auto" when Kate is idle (just the cursor blinking), "xpra info" reports a quality of about ~80% when it looks like it should go much higher (and therefore avoid all flickering by virtue of already being lossless).
PS: The problem manifests even more wildly if kate has spellchecking enabled and some words are underlined.
I don't think there is much we can do about this at all, when using YUV422 or YUV420, the colour subsampling will do this - the only way to avoid it is to not use it: setting a quality high enough so that YUV444 is used (by default the threshold is at 90%).
The quality and min-quality options can be set:
/etc/xpra/xpra.conf
~/.xpra/xpra.conf
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/245