Enable CKEditor toolbar button only with valid text selection?

Question

I\'m working on a CKEditor plugin for annotating text and adding margin comments, but I\'d like some of my custom toolbar buttons to be enabled only when the user has already se

Answer 1

Here is the code required to answer exactly the question using the refresh method as suggested by Gyum Fox.
I mention that to make it work, contextSensitive has to be set to 1.

editor.addCommand( 'myCommand', {
    exec: function( editor ) {
        // Custom logic of the command
    },
    refresh: function( editor ) {
        var editable = editor.editable();
        range = editable.getDocument().getSelection().getRanges()[ 0 ]; // We assume only one range.
        commandState = ( range && !range.collapsed ) ? CKEDITOR.TRISTATE_OFF : CKEDITOR.TRISTATE_DISABLED;
        this.setState( commandState );
    },
    contextSensitive: 1
});

EDIT: I noticed some refresh issues on my side. So, because of that, I'd go for the Marek Lewandowski answer.