Rectangular Selection in the NetBeans Editor

Today I had a strange course in NetBeans. During the blinking there
was a rolling line bar visible. Also the selection was a little bit strange.

I didn't recognize, that also an icon in toolbar of the editor window changed.

The rectangular edit was activated by the key sequence


This allows to do a rectangular select:

and not a selection over the lines.

After the selection you can type words and the whole selection is changed:

Here I entered the word Test.

The selection of this mode is done in the toolbar by clicking on the
icon with the dashed rectangle and the arrow pointer.