Try this...
MCC command 22029 toggles the tree.
Sooo...
In the MC installation folder, there's a "Data" folder. Create a folder inside that called "Custom Resources".
Inside that folder, you want to place a file called Resource.xml
Mine is a simple three thing affair, and is in the attached zip file. It contains the code below...
<MJRS version="1.0">
<ACCELERATORS>
<!-- Global shortcut that begins a Play Doctor session -->
<Entry Key="Ctrl;Alt;R" Command="10047" Global="1" />
<!-- Go to folder containing selected file -->
<Entry Key="Ctrl;Alt;D" Command="26004" Param="-2" />
<!-- Toggles the tree pane open and closed -->
<Entry Key="Ctrl;T" Command="22029" Param="-1" TranslateFlags="23" />
</ACCELERATORS>
</MJRS>
So, close MC, create the folder, extract the xml file into it, and restart MC. Now...
Ctrl+Alt+R will kick off a 'Play Doctor' playlist. This is a 'global' hotkey combo, so will work, as long as MC is running, regardless of which application is currently in focus.
Ctrl+Alt+D will open your default file explorer at the location of the currently selected file, and select that file.
Ctrl+T will toggle the tree open and closed.
If you don't want the other two, simply open the the xml file in a text editor and remove their entries.
Enjoy for the weekend
-marko