LMMS/lmms ? reverse-engineered prompt

Build me a cross platform music making app like LMMS, something people can use to compose, arrange, and mix songs without needing expensive software.

I want a clean interface with a song editor for arranging clips and automation, a piano roll for editing melodies, a beat sequencer for drums and patterns, and a mixer with multiple channels and effects. It should support MIDI fully, including importing and exporting MIDI files, and it should also be able to load common instrument and effect plugins like SoundFont and VST style instruments if possible.

Please make it feel usable for real music production, with a few built in synths and effects so it works out of the box. If you need current implementation details or build instructions, look up the docs online and follow the project’s existing setup.