OK I get why now, the “Keep UV and edit mode selection in sync” option is affecting this addon.
Thanks for feedback! Please, download updated version
UPDATE 1.0.9 (02.06.19)
Fix bug, when “Set TD” work incorrect with “UV Selection sync” option.
Update available for Blender 2.79 & 2.80
WARNING: This last update for 2.79. All future update will be only for 2.8 branch
I have two good news:
I created a public GitHub repository. You are welcome!
Texel Density Checker now available on Blender Market. As paid addon 10$ (addon don’t difference with free version)