Almost all GTK and Gnome applications on Linux use Pango and the Harfbuzz library for rendering. Therefore, if you get Myanmar Unicode support into Pango then you can render Myanmar correctly in a lot of Linux applications and the Gnome Desktop. The default Pango module should work with Padauk 2.6 and Myanmar3. A Pango Myanmar OpenType module is also being developed.
It should also be possible to use KDE with Myanmar Unicode since it also uses the Harfbuzz library for OpenType rendering. Unfortunately, the current KDE code doesn't work properly with existing Myanmar Unicode 5.1 fonts.