Window Closes then Re-opens on it's own; OS X 10.11.6; Mid 2012 MBPro; Opera Beta 45.0.2552.632
Occasionally my window will completely disappear for a few seconds, then reappear all on it's own.
I don't seem to have lost any tabs when it Reloads.
I haven't discerned a triggering pattern yet. This last incident happened when I clicked on the "Opera Beta" Menu to check a setting(never made it to "Settings" and trying again now the window remains as normal.
Also haven't noticed if the Browser is closing completely or just the Window; will try and remember to check next time.
Do you even want reports on the Beta version?