Add check for valid GtkTreeSelection (issue #40)
Add a check to ensure that a GtkTreeSelection is still valid after chaining up. This fixes a bug that was exposed by adding directory specific setting to Thunar (see issue thunar#3521).
Add a check to ensure that a GtkTreeSelection is still valid after chaining up. This fixes a bug that was exposed by adding directory specific setting to Thunar (see issue thunar#3521).