After running KMagnifier you will get a window similar to the one show above. The main window of KMagnifier shows the magnified (or zoomed) contents. We refer to this window as the "zoom window". The zoomed image shown inside the zoom window is captured from a part of the screen. The part of the screen which is magnified is referred to as the "selection window".
You can use KMagnifier to magnify the same part of the screen all the time, or you can let KMagnifier magnify the region around the mouse cursor (think of it as a moving lens). The default mode of operation is the former. To see the marking of the part of the screen that is being magnified, you can select "show selected area". It is always better to turn "show seleted area" off once you know the placement of the selection window.
To magnify the contents around the mouse cursor, select "follow mouse". Now as you move the mouse, you will see that the screen around the mouse cursor is magnified and shown in the magnifier window.
If you would prefer not to see the mouse cursor in the zoomed image, de-select "mouse cursor". Please note that KMagnifier cannot yet find out the current cursor shape. Thus, it shows the default KDE/Qt cursor.
When not in "follow mouse" mode, the selection window can be changed as needed. The selection window can be moved or resized. This can be done using the mouse in the following way:
Left Mouse Button : By keeping this mouse button pressed and moving the mouse, you can grab and drag the contents of the zoom window.
Shift Key + Left Mouse Button or Middle Mouse Button : By using this combination, you can change the position of the selection window on the screen. As soon as you use the above combination, you will see the current position of the selection window. You can now move the mouse to drag the selection window around. When you are satisfied with its position, just leave all the buttons that you had pressed.
Control Key + Left Mouse Button : By using this combination, you can resize the selection window. Keep in mind that the top-left corner of the selection window is kept constant and the bottom-right corner is movable.