Editor hidden tabs (Tab placement: None) in Distraction-free / Zen mode

In IDEA 2020.1 we have changed the hidden tabs behavior in Distraction-free mode which seems to be confusing for some users.

The implemented solution was designed to fulfill the requirement that Tab placement: None should affect only tabs visibility. Besides, we got opposite requests on hidden tabs closing in Distraction-free mode: some expected them to stay behind like in normal mode, while others would like to get the empty welcome screen after closing the active tab. Please refer to this YouTrack ticket and its linked issues for more details. 

How it works now:

• In normal mode:
  • Tab limit configured in Settings is used no matter what Tab placement is.
• In Distraction-free / Zen mode:
  
  • If Tab placement == None, then Tab limit is automatically set to 1
    Example: Open file A, then file B and file C. Close file C - empty welcome screen is shown.
  • If Tab placement != None, use Tab limit configured in Settings
    Example: Open file A, then file B and file C. Close file C - file B is displayed. Empty welcome screen appears only after closing file B and file A.
    Important: Tab placement should be set before entering DFM / Zen mode.
    

If you prefer one of the closing policies and face the behavior you don't like, try exiting the Distraction-free / Zen mode and check the Tab placement property in File | Settings | Editor | General | Editor Tabs.