[Bug] jquery.ui.position.js?ver=3.3.1 line 103

I’m getting this error when the ‘Distraction-Free Writing’ dialog is shown.

Uncaught TypeError: undefined is not a function
https://bb.justgooddesign.com/wp-content/plugins/wp-jump-menu/assets/js/jquery.ui.position.js?ver=3.3.1 line 103

When this error occurs – I cannot dismiss the message and it covers important navigation in the upper left.

Distraction-Free Writing
Enable distraction-free writing mode, and everything surrounding the editor will fade away when you start typing. Move your mouse out of the editor to reveal everything again.

Line #103: marginLeft = parseInt( $.curCSS( this, "marginLeft", true ) ) || 0,
Message: undefined is not a function

Full block of code:

return this.each(function() {
		var elem = $( this ),
			elemWidth = elem.outerWidth(),
			elemHeight = elem.outerHeight(),
			marginLeft = parseInt( $.curCSS( this, "marginLeft", true ) ) || 0,
			marginTop = parseInt( $.curCSS( this, "marginTop", true ) ) || 0,
			collisionWidth = elemWidth + marginLeft +
				( parseInt( $.curCSS( this, "marginRight", true ) ) || 0 ),
			collisionHeight = elemHeight + marginTop +
				( parseInt( $.curCSS( this, "marginBottom", true ) ) || 0 ),
			position = $.extend( {}, basePosition ),
			collisionPosition;

For now, I can disable the plugin to remove the error. Any help is appreciated as this is my favorite plugin to use.

Thanks,
J

https://www.ads-software.com/plugins/wp-jump-menu/