My preferences are disabled.
My problem is solved
I clicked on the green light for the preference until it is black. Restart plsql developer and it works fine.
I have preference "AllowMultipleConnections" disabled.
When I open a sql window with connection "A" and logged on to connection B, the sql window keeps connection "A" (statusbar at the bottom of the window). I thought by disable the preference "AllowMultipleConnections" all windows get...