Description:
Spellchecker isn't triggered to give feedback to the user after each character typed. If you i.e. start scrolling after you mistyped a word, you can easily miss it.

Steps to Reproduce:
Spellchecker used English (USA)

1. Write "This is a test This is a test". Control+enter (for a new page)
2. Change a word in the middle to a word that doesn't exist in the English language. (i.e. the first "test" becomes "testdsfjl")
3. Spellchecker marks the misspelled word when you press any key to change the document. If you scroll with mouse, move cursor with arrow keys, page up/down or click spellchecker isn't triggered.


Actual Results:
Spellchecker doesn't immediately mark an erroneous word with red waves.


Expected Results:
After each typed character the spellchecker is triggered, so you get immediate feedback.


Reproducible: Always


User Profile Reset: No



Additional Info:
Version: 6.4.6.2
Build ID: 1:6.4.6-0ubuntu0.20.04.1
CPU threads: 8; OS: Linux 5.4; UI render: default; VCL: gtk3; 
Locale: en-US (en_US.UTF-8); UI-Language: en-US
Calc: threaded