Is there a place to get/share notepad++ syntax highlighting

Like most other tabbed applications, it's as simple as dragging the tabs out of the active application window. When you release the mouse button, Notepad++ will spawn a new window with the tab you just dragged out. Another way to do this is to select the tab you want to break out, and go to View -> Move/Clone Current Document -> Move to New Instance. You can then tile these separate windows as you would like.

You can also drag the tab within the active window to spawn a split-screen view by selecting one of the two "Move to new view" or "Clone to other view" when you release the mouse button after dragging.

Find your Notepad++ install directory (c:\Program Files or c:\Program Files (x86), typically). You need to edit the language definition file. There's two of them: an ansi file called lang.model.xml, and a unicode file called langs.xml. Most likely you are using the ansi file if you are based in US/Canada.

Open the file in Notepad++, it's a generic XML file and can use the XML syntax highlighting. Search the file for "matlab". This should take you to a block of similar to this:

<Language name="matlab" ext="m" commentLine="%" commentStart="" commentEnd="">
    <Keywords name="instre1">break case catch continue else elseif end for function global if otherwise persistent properties return switch try while</Keywords>
</Language>

Edit the <keywords> section to include the words you want higlhlighted (Classdef, properties, etc.).

Then save the file and restart Notepad++. The new syntax settings should take effect.