Make application background transparent?

[fat_snorlax]

I don’t think it’s impossible, as this post seemingly did it (with some difficulty):

Screen transparent display

I opened this macro LV_COLOR_SCREEN_TRANSP .I want to set the screen background transparent; But after I open this macro, The widget drawn on the transparent background show jagged, not smooth, and the text also shows exceptions. But drawn the background is opaque, it displays normally [pic]

Unfortunately they did not share how it was done.