how to scroll to file in large project where tabs exceed window and drop down

I have just been trying to load some code onto arduino mega for 3d printing.
The instructions are fine telling you which files to edit for the printer you would like create.
However finding the files to edit in the arduino IDE seem near impossible.
For example the marlin firmware is a large sketch with a great many files(tabs).
To open the files you can can use CTRL-ALT_LEFT or RIGHT, or use the drop down menu on the right.
Only the drop down menu does not show the complete list of files as it is larger than the drop down, and there is no scroll buttons on the drop down. To use CTRL_ALT_LEFT or RIGHT you will not the see the name of the file it opens, only it's contents if it is not one of the tabs that fits on the screen.
Itried to search for an answer but the only info I found was write your own IDE or use another IDE.
Now I just want to use an existing project and change a few change a few values in various files, I'm certainly not going to write my own IDE for this. I have spent more time phaffing with this IDE than anything else. Can someone please tell me how to use this insanely poor IDE to simply find a file?
I can't use another version as 1.05 or 1.06 is what they require for marlin.
What options do I have ?

can't access tabs in Arduino.

too many tabs in arduino.

Just open the files you need to edit in a standard text editor and then use the Arduino IDE only to do the upload to your printer.

In windows 8 (and IDE1.6.6), you can use to tab through the files. You can try that for your version of Windows and IDE.

Unfortunately, when you go past the visible tabs, you can not see which file is selected.

Remember that the Arduino is designed to make life easy for beginners; which beginner in his/her sane mind will have 20-plus different files?