The tinymce event system would not pick up the focus within the loaded
draw.io instance, after the drawing toolbar button was clicked, hence
the toolbar would hang around.
This adds a hack to dispatch a mousedown event on the body to get the
toolbar to hide.
For #3597
- Added workaround for new 'srcdoc' usage that's breaking content in
Firefox, added new 'custom-changes.md' file to document for future.
- Updated old usages of 'new' when creating nodes.
- Tested and changed logic, where required, where 'editor.dom.select'
has been used to replace the old '$' usages.
- Fixed bad boolean value being passed to 'setActive' in task list
logic.
- Split everything into specific plugin/concern files to make things
more managable. Means original component file is now simple and much
of the core config is focused in one place.