I recently made the leap from Windows to LinuxMint and one thing that has been driving me mad is the inability to add a DOT while wiring nodes, ALT+CLICK just doesn't work.
LinuxMint seems to be intercepting the ALT keypress before Houdini can process it.
I found the solution:
Go to System Settings > Windows > Behavior and in the Moving and Resizing Windows section, change the binding for Special key to move and resize windows from ALT to Super or Disabled. Super is just another name for the Windows key.