This is the latest release of tinmyce BUT from the changelog - pay special note to the first item in bold

Dropped support for IE 8-10 due to market share and lack of support from Microsoft. See tinymce docs for details.
ADDED an inline boundary caret position feature that makes it easier to type at the beginning/end of links/code elements.
ADDED a help plugin that adds a button and a dialog showing the editor shortcuts and loaded plugins.
ADDED an inline_boundaries option that allows you to disable the inline boundary feature if it's not desired.
ADDED a new ScrollIntoView event that allows you to override the default scroll to element behavior.
ADDED role and aria- attributes as valid elements in the default valid elements config.
ADDED new internal flag for PastePreProcess/PastePostProcess this is useful to know if the paste was coming from an external source.
ADDED new ignore function to UndoManager this works similar to transact except that it doesn't add an undo level by default.
FIXED so that urls gets retained for images when being edited. This url is then passed on to the upload handler.
FIXED so that the editors would be initialized on readyState interactive instead of complete.
FIXED so that the init event of the editor gets fired once all contentCSS files have been properly loaded.
FIXED so that width/height of the editor gets taken from the textarea element if it's explicitly specified in styles.
FIXED so that keep_styles set to false no longer clones class/style from the previous paragraph on enter.
FIXED so that the default line-height is 1.2em to avoid zwnbsp characters from producing text rendering glitches on Windows.
FIXED so that loading errors of content css gets presented by a notification message.
FIXED so figure image elements can be linked when selected this wraps the figure image in a anchor element.
FIXED bug where it wasn't possible to copy/paste rows with colspans by using the table copy/paste feature.
FIXED bug where the protect setting wasn't properly applied to header/footer parts when using the fullpage plugin.
FIXED bug where custom formats that specified upper case element names where not applied correctly.
FIXED bug where some screen readers weren't reading buttons due to an aria specific fix for IE 8.
FIXED bug where cut wasn't working correctly on iOS due to it's clipboard API not working correctly.
FIXED bug where Edge would paste div elements instead of paragraphs when pasting plain text.
FIXED bug where the textpattern plugin wasn't dealing with trailing punctuations correctly.
FIXED bug where image editing would some times change the image format from jpg to png.
FIXED bug where some UI elements could be inserted into the toolbar even if they where not registered.
FIXED bug where it was possible to click the TD instead of the character in the character map and that caused an exception.
FIXED bug where the font size/font family dropdowns would sometimes show an incorrect value due to css not being loaded in time.
FIXED bug with the media plugin inserting undefined instead of retaining size when media_dimensions was set to false.
FIXED bug with deleting images when forced_root_blocks where set to false.
FIXED bug where input focus wasn't properly handled on nested content editable elements.
FIXED bug where Chrome/Firefox would throw an exception when selecting images due to recent change of setBaseAndExtent support.
FIXED bug where malformed blobs would throw exceptions now they are simply ignored.
FIXED bug where backspace/delete wouldn't work properly in some cases where all contents was selected in WebKit.
FIXED bug with Angular producing errors since it was expecting events objects to be patched with their custom properties.
FIXED bug where the formatter would apply formatting to spellchecker errors now all bogus elements are excluded.
FIXED bug with backspace/delete inside table caption elements wouldn't behave properly on IE 11.
FIXED bug where typing after a contenteditable false inline element could move the caret to the end of that element.
FIXED bug where backspace before/after contenteditable false blocks wouldn't properly remove the right element.
FIXED bug where backspace before/after contenteditable false inline elements wouldn't properly empty the current block element.
FIXED bug where vertical caret navigation with a custom line-height would sometimes match incorrect positions.
FIXED bug with paste on Edge where character encoding wasn't handled properly due to a browser bug.
FIXED bug with paste on Edge where extra fragment data was inserted into the contents when pasting.
FIXED bug with pasting contents when having a whole block element selected on WebKit could cause WebKit spans to appear.
FIXED bug where the visualchars plugin wasn't working correctly showing invisible nbsp characters.
FIXED bug where browsers would hang if you tried to load some malformed html contents.
FIXED bug where the init call promise wouldn't resolve if the specified selector didn't find any matching elements.
FIXED bug where the Schema isValidChild function was case sensitive.