Playing some catchup! Sorry for the brief absence, I'm back now
@simplypro @ChrisLaw did a great job answering your question, but if you're still confused let me know and I'll make a little guide with screenshots!
@bhw the blue icons are all in base64 text inside the volume up button's script. You could convent them back to images, change their color to red in your preferred image editor, then _re_convert them back to base64 and replace them in the volume up button. IMO it's not worth the effort, but if you are very determined to have something all-red then it is technically possible! The code (with base64 images inside) is here:
@adam2780 I'll add GoToMeeting in the next experimental version! As for Slack, it was that way in previous versions, but I felt that since the call feature of Slack is less used there wasn't a reliable way for me to know if a user actually needed the mic mute button in Slack. I wonder if there's a way for me to detect that Slack is on a call? Or, even better, that the microphone is in use...
@Cooluck the best way is first to use the built-in GC-BTT settings menu (cmd+opt+shift+p). Every setting set through that menu will persist between upgrades. There is no need to deleted "unused" widgets or widgets that you've turned off, since they won't run in the background or anything (I've made sure of it).
If you want to do deeper customizations, such as adding whole bits of functionality or altering the UI, I recommend making your own separate preset and augmenting GC-BTT inside your separate preset. This way, when you upgrade GC-BTT you won't remove your custom widgets. (In the same vein, if you want to modify a GC-BTT widget, you can copy it into your own preset and uncheck visibility of the GC-BTT one. But note that your copy won't obey any settings set through the settings menu.)
I'm slowly building up an FAQ but I will also make sure to eventually include some deep customization tips/instructions. No date on that, but it'll arrive sooner or later!
Finally! A question for @Andreas_Hegenberg - did you get the chance to look into my initialization question? I really, really want to solve that ASAP and get a stable version out.