Window Size issue

After connecting my macbook to a monitor via hdmi, the soulseek program window has become incrediby wide, rendering it unusable. Ive uninstalled and reinstalled the program several times with no luck. Any ideas on how i can fix this? (screenshots below) Thanks!

under Windows such Infos are stored in the user profile and with alt-space U could trigger the resize function. Don't know how it is done in OSX...