I've tested and modified the desktop file. The gui launch ok just remove the sudo in the exec line.

Edit1:
I can't save setting from editor

Test in xterm with root privilges: "chown user:users /home/user/.config/savepress"
I can now save setting from editor, but editor on next start doesn't show or not load the new setting only the default vallue.

But savepress load the new setting when i long press the right button.