FVWM: Intellij focus issue

Hi Everyone,
I'm having an annoying issue. I'm using FVWM3 (used FVWM2 up to a week 
ago and experienced the same) and when I'm coding in Intellij:

     - if there is a suggestion pop-up and my mouse cursor is there 
where it pops up
     - The main window doesn't lose focus (but up-down keys select among 
the suggestions)
     - and if I continue typing, finish the word, or select a 
suggestion: my cursor *disappears*
     - interestingly I can still use delete and can step up-down (the 
row highlight changes), but there is no cursor, and I cannot type new 
characters
     - the same doesn't happen if the cursor is at any other location, 
not over the pop-up -- e.g. if I select a suggestion with up-down+enter, 
the cursor still blinks in the main text area


As you can imagine, this is a very annoying. I tried a few things, like:

         Style "jetbrains-idea"                SloppyFocus, GrabFocus
or
         Style "jetbrains-idea"                ClickToFocus


But none of these helped and I'm not sure where to continue. I was 
wondering if anyone has a suggestion to fix it.

Oh, and a +1: another interesting thing, is that menus in like Firefox 
or Thunderbird menus show up with around 50% transparency, and any 
non-focused window has the same. Focus takes it to 0%. I'm using:

      compton -b --backend glx --glx-no-stencil --shadow-exclude "g:a:Fvwm"

If I kill it, all transparency is gone, even in my urxvt where I 
intentionally set it up. Not sure if this is an FVWM issue (probably 
not) but I didn't remember having this problem only since a few months ago.

Thanks for any suggestions!
Szabolcs