TinyMCE not fullscreen on Bootstrap theme

TinyMCE doesn’t display full on Bootstrap theme due to the z-index is set lower than in Bootstrap components. To fix that, update the z-index:

.mce-fullscreen {
    z-index: 1050; // or any higher value
}

How about keeping the navbar or sidebar displaying while on fullscreen-mode editor?

The solution is to set the position for .mce-fullscreen, because .mce-fullscreen is set with position: fixed.

div.mce-fullscreen {
    z-index: 1050;
    top: 51px!important;
    left: 231px!important;
    right: 230px !important;
    width: calc(100% - 231px) !important;
}

Since TinyMCE will calculate width is 100% of the screen, but we want to keep sidebar and the editor in viewport, so use calc() to reduce width of the editor to fit screen.