I would like a terminal for Ubuntu that supports PgDn and PgUp as the default functionality and to send them to the current Unix application when you press PgDn+Shift.
If you go back to the original terminal emulator, xterm, you can specify any actions for the keys. For example,
xterm -xrm 'XTerm*VT100.Translations: #override\n\ ~Shift <KeyPress> Prior: scroll-back(1,halfpage)\n\ ~Shift <KeyPress> Next: scroll-forw(1,halfpage)\n\ Shift <KeyPress> Prior: string(0x1b)string("[5~")\n\ Shift <KeyPress> Next: string(0x1b)string("[6~")'
This will scroll back a half page when the Prior key (page-up) is pressed without Shift, and insert the escape character and
[5~ when pressed with Shift.