User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Firefox/38.0 Build ID: 20150525141253 Steps to reproduce: openning thunderbird. do nothing and waiting! Actual results: + All thunderbird windows become smoothed, as is smooth procs is restarting without refreshing windows content. Windows become unreadable. + controls an objects are clean again when mouse gone on it (refresh) but only them. Expected results: + there is some smooth on smoothed, on smoothed, on smoothed.. etc... maybe is better to smoth on refreshed clear window...

The probleme can be resolved by setting gfx.direct2d.disabled true and layers.acceleration.disabled true using the config editor. You can verify this by looking at the "GPU Accelerated Windows" line in the graphics section near the bottom of the screen for help -> troubleshooting information. It is set to 0 if hardware acceleration is off.

Seen on materials: ------------------------------------------------- - NVIDIA GeForce GTX 765M - win 7 Home (alienware 14" 2013), core i7 4800.

morel, Do you still have problems in version 45 with HWA enabled? If you do still see problems, is it better with (in this order) 1. current beta version from http://www.mozilla.org/en-US/thunderbird/channel/ ? 2. latest NVIDIA driver (As of Dec 14, 2016 driver version is up to 376.33) ?

Morel seems to be gone. If anyone still sees this problem please comment so we can investigate