The AppLock plugin holds a window in place such as a web browser or file manager and locks it inside EditPlug for easy access. Often you will need to manage windows on your desktop manually while viewing two windows at once, whereas AppLock manages the window for you.
If for example you are using Mozilla Firefox to preview your html files, why not lock it inside EditPlug for convenient access instead of Alt-Tab-ing and getting frustated managing windows with your mouse.
To lock a window inside EditPlug, launch the AppLock plugin and then click the Lock App... button. To unlock a window and send it back to the windows taskbar, click the Unlock button.