Hello all,
First, many huge thanks to people hard-working on QubesOS. I’ve been using it as my working environment for over 2 years, and it’s a secure, reliable, stable, robust, and very convenient OS (tons of little details make life easier).
Without enshittification (which is rare, precious, and great).
I managed to do what is in the title of my post in the 4.2 versions, but can’t remind nor find how to do so in my brand new 4.3.1 install.
If anybody can help.
Cheers,
This question is about xfce, not about qubes.
Hi @kpiris,
For sure it’s a “xfce in Qubes OS” thing. 
Thanks for your help in clarifying that.
(I have updated the topic title)
Cheers,
Try system settings > window manager > advanced > window snapping
Snapping does not maximize (equivalent to Alt+F10) the window.
I had similar hiccups with window snapping after updating to r4.3, but maximizing happened to just work (snap to the edge did not). I also have windows extending beyond the bottom of the screen. xfce forum or search engine is likely the quickest route to a fix..
“automatically tile windows …” in accessibility tab of window manager tweaks
Thanks a lot! 
My interface is in French, but I finally recalled going through
« Peaufinage des fenêtres » (Windows Tweak)
rather than
« Gestionnaire des fenêtres » (Windows manager)
in
“Systems settings”.
It looks like I had a temporary bug:
Unchecking & rechecking the item made it work as it used to.
Cheers,