Why is is not possible mark text in my Terminal window anymore? I am an eager Terminal user on Mac OSX Yosemite. From time to time I mark text in the Terminal window to copy(right click or cmd+c) onto the clipboard.

For some reason it suddenly stopped working! I can not mark text in the terminal window anymore by clicking and dragging the mouse. I have been looking for a way to turn marking off an on(on Windows Command line tool there is such a setting for some reason), but I cannot find any option for controlling this.
Even though it is not possible to mark with the mouse, I can select "Edit"-"Mark everything"(freely translated from the Norwegian OSX version :)) from the file menubar at the top of the screen - and mark everything works fine. I can see everything marked and I can copy and paste as expected. There is however no way I can affect the marking with the mouse - after marking everything it cant be unselected with the mouse. 

Does anyone have any tips for how to enable marking with clicking and dragging the mouse again?
Sometimes things go wonky in the preferences files and you need to delete them to get things working properly again. Once you restart the app, it will rebuild it's preferences.

Try this:

Quit Terminal completely and then delete this file:
(your home folder)/Library/Preferences/com.apple.Terminal.plist

Hopefully that works for you! If you can't see your library folder, follow this quick guide.