Thanks for the nice screenshots, made this very easy to find:
From what I can tell, you seem to be using “Set Render Opacity” to hide/show widgets. While this works for the rendering part, the “mouse interaction” logic doesn’t care about rendering and instead uses a “hit grid” based on all alive widgets. To affect both visibility and mouse interaction, use a Set Visibility node (see image):
Additionally, widgets also have this “visibility” exposed as a parameter in their details panel, so if you change that it’ll come in effect as soon as simulation starts.
For the other question, your solution seems fine tbh. If you have some unrelated menus and you want them to be exclusive, just do it manually, which should only be a few nodes of logic anyway. There are some built-in options with CommonUI and “activatable widget stacks”, but I wouldn’t recommend it.