“The tab menu gets stuck on top of the foreground app when you switch apps on OsX. ”

I get the same “problem” on windows plus more.

If I open any pulldown menu and at the moment decide to switch to another app…that pull down menu persists on top, unless I took the extra step to minimize Houdini.

It can be annoying but ironically has proven usefull at times;

Can't remember the exact details but it was something like the pulldown menu persistantly showing a file that I can use as reference(works well for a poor memory) while I am searching my own file directories for “comparison”

You might want to start with Substance Painter instead of Designer too. At Siggraph Allego told me Painter would export .sbsars soon (and you could pull them into Houdini with the Substance plug-in).

Artye
A great shortcut to upgrading materials and rendering would be use a Substance Designer with the Houdini plug-in, and, Octane or Redshift. Then when they are too limiting you can move into Mantra