fixes cursor being at 0 position even when text is present, especially annoying for handheld devices with kde virtual keyboard, which is pretty bad, with no way to move the cursor or delete text backward
Reviewed-on: https://git.ryujinx.app/projects/Ryubing/pulls/25
no way this was working before, and if it did, just pure luck, unsafe blind copy of bytes as is and zero checks.
i only tested tomodachi, but should fix all games that were crashing on saving screenshots
the crash was happening because the screenshot buffer was bigger than the bitmap buffer, so marshall.copy() was raising an unhandhled expection crashing the emu.
on top of this, because the data was just copied as is, the result image was garbled.
[fixes#304](https://github.com/Ryubing/Issues/issues/304)
Reviewed-on: https://git.ryujinx.app/projects/Ryubing/pulls/18
