How? you know what was there originally and where it's at... just refresh the overwritten data. It works for me and I have about 4 of those displays in use.
I am writing a GUI with pop up touch screen keyboard etc. The library pop up routines will not know what has been draw but I have had a think about the way I am doing everything and will have objects for everything on screen so I can cycle through them redrawing any that have been overwritten. Being able to read the screen would just have made things simpler especially if I were to implement a mouse pointer.