Simredo has a spell checking function. The screen shot above shows misspelled words underlined in red. Currently, spelling dictionaries for English, Esperanto and Latin are included.
Since version 4.7, it is no longer necessary to install spell check dictionaries. The install-program copies external dictionaries (*.zip) into the folder 'simredo'.
To activate the spell checker, select 'Spell Check' under the 'Other' menu. There are four choices: Off, English, Esperanto and Latin.
Attention Esperantists: It is now possible to register unknown words into Esperanto spell checker. Details are here.