This dialog will open if user keeps touch input active on a button from `bookBtnArray` for >= 500 ms.
'Pin' and 'More info' operations are currently not implemented.
This commit also fixes a segmentation fault that would be caused when deleting libraryWidget (Gutenberg) that first appeared in 4a104522f5.
TODO: Handle what happens when there are no books in the library
TODO: Re-generate database upon exiting USBMS session or books download (libraryWidget)
TODO: Adjust various icon width/height variables depending on the device
A local books database is maintained at `/data/onboard/.inkbox/LocalLibrary.db`. It contains compressed JSON read by the GUI.
URGENT TODO: Fix `*** Error in '/mnt/onboard/.adds/inkbox/inkbox-bin': double free or corruption (out): 0x00648708 ***` error whenever we try to delete localLibraryWidget
