Leaving fullscreen mode does not make side-by-side view disappear

[Situphen]

Describe the bug

If you are in fullscreen mode with side-by-side view and you leave fullscreen mode, the side-by-side previsualization stays on half the page

To Reproduce
Steps to reproduce the behavior:

1. With sideBySideFullscreen set to false
2. Go fullscreen mode
3. Activate side-by-side view
4. Leave fullscreen mode

Expected behavior
Side-by-side view should either disappear or be restricted to the editor

Screenshots

** Version information **

• OS: Ubuntu Budige 20.04
• Browser: Firefox 85
• EasyMDE version: 2.14.0

Additional context
Add any other context about the problem here.

[Situphen]

I am not reproducing on https://easy-markdown-editor.tk/ so I guess the issue is on my side, so I am closing for now.

[Situphen]

I am reopening because I can reproduce it on https://easy-markdown-editor.tk/ when sideBySideFullscreen option is set to false.

[Ionaru]

@Situphen Can you please describe the steps you took to reproduce it?

[Situphen]

You can use this code:

new EasyMDE({
    autoDownloadFontAwesome: false,
    element: document.getElementById('mde-demo'),
    initialValue: '# EasyMDE \n Go ahead, play around with the editor! Be sure to check out **bold**, *italic* and ~~strikethrough~~ styling, [links](https://google.com) and all the other features. You can type the Markdown syntax, use the toolbar, or use shortcuts like `ctrl-b` or `cmd-b`.',
    sideBySideFullscreen: false
});

And try these steps:

1. Click the Toogle Fullscreen (F11) button to enter fullscreen
2. Click the Toogle Side by Side (F9) button to enable side by side mode
3. Click the Toogle Fullscreen (F11) button again to leave fullscreen

[smundro]

This appears related to my #286 PR, which stopped toggling side-by-side when toggling fullscreen when sideBySideFullscreen=false, which apparently leads to the side-by-side state getting out of sync.