Smarter delete key behavior

[nkrusch]

Some displayed characters are actually composed of 2+ unicode characters.

If user deletes this kind of compound-character, the delete operation should be smart enough to know how many chars to remove (not always 1).

[nkrusch]

Study this example that uses a StringBuilder to hold state: https://android.googlesource.com/platform/development/+/master/samples/SoftKeyboard/src/com/example/android/softkeyboard/SoftKeyboard.java

[nkrusch]

𝕀 𝕙𝕒𝕧𝕖 𝕥𝕠 𝕙𝕚𝕥 𝕓𝕒𝕔𝕜𝕤𝕡𝕒𝕔𝕖 𝕥𝕨𝕚𝕔𝕖 𝕗𝕠𝕣 𝕖𝕒𝕔𝕙 𝕔𝕙𝕒𝕣𝕒𝕔𝕥𝕖𝕣, 𝕒𝕟𝕕 𝕀 𝕒𝕞 𝕠𝕗𝕥𝕖𝕟 𝕞𝕚𝕤-𝕥𝕠𝕦𝕔𝕙𝕚𝕟𝕘 𝕝𝕖𝕥𝕥𝕖𝕣𝕤.

Received this from user. First issue has to do with this backspace; second is with key size.

[nkrusch]

Is there any way that the backspace key could perform a 'double backspace' when the character to be deleted requires it?

[nkrusch]

want the text to be deleted letter by letter so I don't end up with the weird question mark things.

[nkrusch]

ᴡʜᴇɴ ɪ ᴘʀᴇss ʙᴀᴄᴋsᴘᴀᴄᴇ... ɪɴ sᴏᴍᴇ ᴀᴘᴘs𝕟𝕛� < --- 𝕚 𝕘𝕦𝕖𝕤𝕤 𝚏𝚘𝚗𝚝𝚜. 𝚝𝚑𝚎 𝚋𝚕𝚊𝚌𝚔 ? 𝚍𝚒𝚊𝚖𝚘𝚗𝚍 𝚊𝚙𝚙𝚎𝚊𝚛𝚜 𝚏𝚒𝚛𝚜𝚝, 𝚝𝚑𝚎𝚗 𝚒 𝚌𝚊𝚗 𝚋𝚊𝚌𝚔𝚜𝚙𝚊𝚌𝚎 𝚝𝚑𝚎 𝚍𝚒𝚊𝚖𝚘𝚗𝚍.

[nkrusch]

moving this along again to next

[NA0341]

Issue #122 is a duplicate with a more precise title.

I suggest adding (deletion bug) to this issue and closing #122.