When you have multiple editors and have text selected in both editors, after pressing a button from the toolbar it applies to both editors not just one.
Steps to reproduce:
Open example file examples/multiple-editors.html
Write text in first editor and select it
Write text in second editor, select it and press one button like "Bold"
Text in both editors are afftected, should have effect only in second editor.
When you have multiple editors and have text selected in both editors, after pressing a button from the toolbar it applies to both editors not just one. Steps to reproduce: