Apps with 'Fully customizable interface' feature

DeaDBeeF is a lightweight graphical music player created for easy playback of music and management of playlists. It supports major audio codecs and tags, global hotkeys, gapless playback, streaming audio, command line control, and has an 18-band equalizer.

xplorer² is a desktop file manager combining the simplicity of Windows explorer with the speed and efficiency of traditional dual pane file managers.

Super lightweight (~ 1/3 MB) yet flexible and powerful soft keyboard. Plus an English plugin still less than 1 MB. (Swype ~15 MB, Minuum ~18 MB, Google Keyboard ~15 MB, Swiftkey ~8 MB, TouchPal ~ 8.5MB)

Navitel Navigator 11 is a precise offline GPS navigation, up-to-date online services, and detailed maps of 67 countries and territories of the world. 7 days free.