hi,
i don't rally like the design, so I create a new theme. Can I add more Icons without programming knowledge? For example in the menu "File> Import" (in front of "Import"). And How can I do that?
You can add a new skin for existing icons. but you can't add new icons and apply them to the application without develop.
To add a skin, you have to create the folder at
[APPLICATION_PATH]/share/skins/[your_skin_name]
then just create the icons, using same names as other skins have.
Note that the "text file" skin.properties, is used to provide the skin info such as name, author, description.. etc..
Then when you restart tuxguitar, if you go to Tools -> Settings, you'll see your skin available at "Skins" section.