alpha systray - bakkeby/patches GitHub Wiki
This is a variant of the systray patch that is applied on top of the alpha patch.
One of the key differences between this patch and the https://dwm.suckless.org/patches/systray/ patch is that the latter resizes the bar to give room for the systray window on the right hand side.
This patch, on the other hand, keeps the bar size as-is, and instead reserves space within the bar for the systray (essentially drawing a blank background in that area) and then keeps the systray window on top of the bar. That way when the systray icons are transparent the bar below will be shown.
Note that if not using a compositor the systray icon background will be black.