This is an additional improvement needed from (MDL-42684).

Additional improvement needed for TinyMCE width:

1. Each time the toggle button is click, the width of tinyMce area getting wider.
2. Improve display cut-off in arialist (and binarius). In course/edit.php, when using 3 layers icon tools, some icon get cut-off. It also effected the display of file manager where the list options icons (top right icons) disappeared.

I'm using 1024 display width to replicate this. *attaching screenshot.