Second shot! 
So I finally could replace 2 apps for one, namely Multitouch and Moom, for BTT but now I'm having a conflict?
I'm using the same shortcuts (key combinations or bindings) as I was using in the other ones, which are:
⌃ ⌥ ⇧ arrows to move windows and
⌥ ⌘ ⇧ arrows to resize windows
Anyway, any shortcut I added to BTT is not showing in Keycastr! What have I done, where did I click that is triggering this behaviour?
Thanks in advance!
Keycaster is working at a layer where it won't see keyboard shortcuts handled by BTT. I don't think there is a way to workaround this, as BTT needs to work one layer below such apps to be functional.
You could use the "Show HUD" action in BTT instead.
It's weird because Keystroke Pro shows some of them, it misses the arrows only…
But you pointed to something that could be interesting. Can BTT show keys pressed on screen? Do I need to configure one-by-one? I will presume you know Keycastr, and/or others. Can I achieve the same in BTT?
Currently only one by one with the show hud action. However I plan to make it possible to easily show pressed keys soon.
Then Keycaster Pro possibly works on the same level as BTT.
It could also depend on which app was started first, BTT or Keycastr.