marked it os-x, not sure if it happens anywhere else .. this is in Processing 0123.

i've been hunting on how to trigger this one for a while. it happend so often to me and i
never figured why it's happening. here's the story:

make a new sketch (or open one), type something in over multiple lines until the textfield
starts to scroll. place the carret somewhere before the end of the text. now save and while
the editor is saving switch into another application. once the editor finished saving grab it by
it's title-bar and move the window downwards. all of a sudden the textfield starts selecting
everything from the carret upwards.

this has another problem: sometimes i can't enter newlines after that happened. the
selection goes away when i click into the text, then it reselects as before when i release the
mouse-button. ... or if you make a new sketch after that happened, you will not be able to
enter newlines into it.

will attach two movies showing the bug.

edit]
screen capture movie showing bug

this shows the selection happening after saving, then switching to another app
and coming back ...

edit]
screen capture movie showing follow-up bug

shows the can-t-enter-newlines follow-up.
i was trying to enter:
d
d
d
not:
dddddd

just realized that the same thing is happening when you:

run a sketch ( in my case in processing.core.PApplet ) and return to the editor by clicking it's
titlebar and pulling it downwards. happens regardless of having saved or not before leaving the
editor.

confirmed. the sketch needs to be running from the draw() loop (noLoop
doesn't seem to cause trouble).

i'm guessing, though not certain that this is macosx-specific, and related
to problems with how osx java handles mouseEntered/mouseExited. similar to
the problems in bug #170.

does this still happen?

no, can not get it to happen anymore.

great, thanks for checking.