All the layout/alignment changes are excellent. Nice work!
For the module on/off status, I tried to put myself in “this is my first interaction with RawTherapee” mode, both as someone who at least read Getting Started in RawPedia and as someone who just installed and launched the package and tried to figure it out by poking around.
The on/off controls are referenced in the fourth paragraph of “Edit your first image” on the Getting Started page, including a little visual of the controls. The text doesn’t hit the reader over the head with the fact that tools tend to be “off” initially, and using their controls will have no effect until they are turned on. Common sense would suggest people would realize that, but it seems that this must often be explained. I think most users that read Getting Started should be OK, though.
For new users that just jump in without reading anything, it’s another story. If the user opens his/her first image, and all the tools they see are powered off, e.g.,
it’s not obvious that the is a power button. I suspect that this leads to a lot of the misunderstandings, and I think using a dimmed power button as darktable does for a powered-off tool would reduce the number of confused new users.