Closing a Text Document clears icon of previous Schematic Tab

[in3otd]

I've noticed that closing an (unmodified) Text Document clears the diskette (modified) icon of the previous Schematic Tab.

Steps to reproduce:

• open a Schematic and modify it: the diskette icon in the schematic tab will'appear to indicate that the schematic needs saving.
• open a new Text Document (Ctrl+Shift+V)
• close the Text Document just opened
• note that the diskette icon of the Schematic has disappeared

Will try to push a fix later.