When two or more documents are opened simultaneously, the Arrange All option provides easier navigation than toggling between the opened documents.

To keep multiple documents open in the text window, go to Window in the menu bar and click on Arrange All. You should be able to see all of the opened documents contained in their separate windowpanes. To make one document active, just click anywhere within the document's window and the title bar will become highlighted. You are then ready to edit the text. Close each document individually once you are done.

To change the size of the windowpanes, move your mouse over to the edges of the selected document until you see a resize pointer (up and down arrow cursor). With your mouse button held down, move the resize pointer to the desired location. This method will allow you to size the opened documents to suit your needs.