Can't TYpe in Property Fields
 

Every now and again, I am unable to type into the Properties: Geometry fields.

I can select values with the mouse and they highlight, but I can't type into the fields using either the keypad or number rows.

I don't know how it is getting into that state (must be a keyboard command I am using or something).

I don't know if it is related or not, but when this is happening, I also notice my cursor changes to what looks like the Style Brush.