RMG v0.3.4 is released. Rosalie's Mupen GUI is a free and open-source mupen64plus GUI written in C++. It offers a simple-to-use user interface.

RMG changelog:
Fix mapping button size increasing when reloading settings in RMG-Input
Fix analog stick mapping in-game when having buttons and axis bound in RMG-Input
Fix height mismatch of "Profile" and "Input Device" UI elements in RMG-Input
Fix updater script not using the correct path seperators on Windows
Fix GLideN64's per game settings being overwritten by the updater on windows (or not being updated on linux, see gonetz/GLideN64#2756)
Fix "Automatic" input device not opening controller device when clicking on 'Refresh' in RMG-Input
Fix game specific profile having unexpected UI behavior in RMG-Input
Fix cancel and close button not working correctly in RMG-Input
Fix profile saving not working correctly when having the same profile selected for multiple players in RMG-Input
Add "Filter Events Based On Joystick Type For Buttons" setting to RMG-Input
Add "Filter Events Based On Joystick Type For Axis" setting to RMG-Input

Download: RMG v0.3.4
Source:Here