I'm wondering where the old "invert colors" feature from MS Paint has gone. My new version of MS Paint 6.1 doesn't seem to have this feature?
32 Answers
Right-click!
Actually, the option still exists, but it's not found on the ribbon. You can only find it when right-clicking an image:

The result:

If you select everything or nothing, the entire image is inverted. Else, only the selection gets inverted:

The result:

You can use the keyboard shortcut Ctrl+Shift+I.