Bump version up to 0.3.0
Update required GTK+ version
Add new button for creating new signature
Add dialog for editing signature
Change variable to static
Use stored parent widget for modal window
Place widgets for editing signature
Add news
Add widget to specify signature file
Add widgets to hold access later
Adjust dialog window size
Disable signature selection from file on default state
Add callbacks for selecting signature file
Add signature file selector
Fix wrong signal name
Add debug macro
Store widget pointer which is used when toggle signal is emitted
Change signal handler's type of argument
Use more proper name
Follow changed widget name