Test 1 Write some text in Atto Style the text so that at some places you combine multiple styles List with bold items Link that is italic Bold + italic + underline Make sure that when you move the cursor, the buttons are highlighted accordingly (each style should highlight its corresponding button) Test 2 Add the following HTML using the HTML view <br> <b>test</b> <br><br> Make sure the "Bold" button is only highlighted when the cursor is in the bold area, not at the beginning or the end of the content Test 3 Select some text without style in the editor Click the bold button and make sure the button is highlighted Make a link Select the link and click the unlink button Make sure the unlink button is not highlighted Test 4 Enter A LOT of text in the editor, and add many styles, lists, images, etc... CTRL + A to select the whole content Make sure the browser does not freeze, and the buttons are highlighted as you'd expect (note: MDL-45403 ) Change your selection, and make sure the browser does not freeze