In-line Spell Check .. Things you should know

1) in order to use the in-line spell check, you MUST have a dictionary selected
... click on the 'spell' icon in the composer window and select a dictionary from the drop down in the lower left of that window

2) to enable/disable the in-line spell checker press ']' three times on a blank line
... you will see (briefly) the status of the in-line spell checker as 'ILSC on' or 'ILSC off'

3) to enable/disable the in-line spell checker's debug to file press ']' two times and [ one time on a blank line
... you will see (briefly) the status of the in-line spell checker as 'ILSC debug on' or 'ILSC debug off'
... you might be asked for a path to the debug file the extension will create
...  once you have inserted a path, it will always use that file and recreate it if it is deleted

4) to switch languages in the in-line spell checker press ']' two times followed by a number 0-9 
... the numbers correspond to the order in which you installed the dictionaries 
... you will see (briefly) the selected dictionary in use as 'ILSCLang = en-US' for USenglish or 'ILSCLang = nl' for Dutch etc.

5) to enable/disable the autocomplete press ']' two times and '=' one time on a blank line
... you will see (briefly) the status of the in-line spell checker as 'ILAC on' or 'ILAC off'
... in order to use the autocomplete feature, you MUST have an autocomplete file saved and pointed to by the extension's settings
... use the settings dialog to set/reset/change all of the autocomplete entries

6) to bring up the autocomplete settings (the prefs dialog) on-the-fly, press ']' two times and 'o' (the letter) one time on a blank line
... the settings dialog will appear 
... if you click the 'save list' button, the changes will immediately be reflected in any compose windows you have open

7) to use the suggestion dropdown one a marked misspelled word, 
...just position the insertion point in or just next to the word and press ctrl-space ( Mac users press Command-space )
... then use the up/down cursor keys to select the word you want and press enter to replace the misspelled word
... if none of the words fit the bill, press ESC

8) to add a word to your personal dictionary,
...perform the steps in 7 above but instead of pressing enter on a suggested word, 
......press enter on the item that has a + to the left of the word, meaning add 

8) to ignore a word for the rest of that compose,
...perform the steps in 7 above but instead of pressing enter on a suggested word, 
......press enter on the item that has a ~ to the left of the word, meaning ignore