Scrolling is disabled all of a sudden in terminal

Question

Sometimes I use the terminal (konsole) and all of a sudden the behaviour when mouse scrolling goes from scrolling through past output to scrolling through the history on the command prompt, and there is no way to see the past output anymore. (The scrollbar is still there but it is as if there were no past output)

Since it only happens sometimes, and if I open a new subwindow it defaults back to scrolling through past output, I am guessing I am inadvertently hitting some shortcut that toggles between these modes, but I can't find out which shortcut it is.

How can I get out of this weird scrolling through history mode?

Answer 1

Perhaps you ran a subshell from an editor, and it left the terminal in the alternate screen. You can test that by

tput rmcup

which would return to the normal display.

While in the alternate screen, some terminals may override the scroll-wheel action by sending up/down cursor escapes.

Answer 2

If tput rmcup won't work then try closing all the terminals and then use new terminals.