Fix compatibility issue with input methods when checking availability

[ghost]

This bug happens when using an input method that uses in-place marked text, Chinese pinyin for example. When the user selects a word, the .editingChanged action gets triggered twice simultaneously (with the same text), which causes the availability checker to stop until the text's changed again, as the video shows below:

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}