Comment 1 for bug 1779575

I'd say this behaviour is party intended and partly a bug:
the lower half was constructed this way to avoid squeezed samplers or Mic units, but the settings don't persist when the skin get's resized/redrawn or when Mixxx gets restarted.

Other skins don't have this 'protective' mechanism, so how to proceed?
a) We could allow to enable all widgets regardless of the available screen space, some widgets get squeezd and users need to decide what to resize (waveforms, less FX units) or what to disable so everything fits nicely.

b) IDK how difficult it is to put FX units, samplers & Mic/Aux into a scrollarea. Also I'm not sure if a scrollarea would improve the UX significantly: unlike the library, it's tricky to use touchpad or scroll wheel inside that area since (while scrolling) users might accidentially hover knobs or sliders which would then catch the scroll events.

So IMO a) is the way to go (for now).