I would recommend you Notepad++.
It is light, fast, powerful and is one of the best tool for programming.
It helps reduce the worlds carbon-dioxide emmition!!!
Notepad++ is a free (as in "free speech" and also as in "free beer") source code editor and Notepad replacement that supports several languages. Running in the MS Windows environment, its use is governed by GPL License.
Based on the powerful editing component Scintilla, Notepad++ is written in C++ and uses pure Win32 API and STL which ensures a higher execution speed and smaller program size. By optimizing as many routines as possible without losing user friendliness, Notepad++ is trying to reduce the world carbon dioxide emissions. When using less CPU power, the PC can throttle down and reduce power consumption, resulting in a greener environment.
I did not understand the first feature you wanted, but if this helps, Notepad++ lets you open multiple programs in different tabs. So you could easily shift between them.
The Full Screen view of Notepad++ satisfies your second requirement.
Hope this helps =)