CombineZM only uses one window, there is no toolbar and no information is presented at the bottom of the window, all of this leads to an uncluttered appearance designed to maximize the area available for what's important, your pictures. To further reduce clutter I have used the title line, the bit across the top that usually tells you the name of the running program and the name of the document you are working on to show additional information.
Starting from the left of the normal display, just after the CZ icon 'T=none' is often displayed this means that there is no Tool active at the moment, say you click on Contrast on the rectangle menu none will change to Contrast. This means that pressing the Left and Right Arrow keys or 'M' or 'N' will cause the Active Frame to be altered by the Contrast function, actually the frame stays as is but the adjusted version of it is copied to Out. 'Escape' abandons the current Tool, pressing Return gives you the option of saving the changed version in place of the original frame. If you move to another frame with the Up or Down Arrow keys before pressing Return you can apply the same changes to that too, in fact you can alter the whole stack in this way, one frame at a time, if you wish.. Most Tools behave in the same or a similar way.
The next item on the Title Line is usually 'M=Select' this means that using the left mouse button and mouse pointer combination you can select a rectangular region, indicated by a dotted line, this region is called the Active Rectangle and is usaed by the functions on the Rectangle Menu and some others such as Save Rectangle As. If you press the Right mouse button once after selecting a rectangle in this way, and if the rectangle is small enough you will see a magnified view of it. 'M=Paint' will now appear on the Title Line this means that you can Paint pixels from the Active Frame onto the Picture using the Left Mouse Button. In a similar way you can Fix pixels in the picture when 'M=Fix' appears 'F' is a toggle key that changes Paint into Fix and back. If you hold Shift down while Fixing or Painting you will Unfix or Delete pixels in the Picture.
Next along the title line 'VFull=picture' means you are looking at a View of the Picture, the word Full after V indicates the picture may have been shrunk or stretched but the entire picture is visible. Press TAB and notice the change, in place of picture the name of the Active Frame is displayed, again press 'O' and Out is displayed.
CombineZM has three different views, when you start you will be in Full View VFull=..., pressing the right mouse button once as explained above puts you in Magnified View VMag=..., and finally pressing the same mouse button puts you in Normal View VNormal=.... In Normal View every pixel on the screen corresponds to one pixel in the picture, this means you may not be able to see the whole of a big picture, or a small picture will appear at the upper left corner of the display area. Scroll Bars will appear when necessary to move around a picture, and there are Page Up and Page Down keystrokes available. Note there is no distortion in Normal or Full view but Magnified View represents each pixel as the largist sized rectangle possible this may not be square.
Pressing 'F' for Fix as explained above creates combinations like 'VFixedFull=picture' This means Fixed pixels will be made visible, pressing 'F' again reverts to normal.
Pressing the letter 'P' puts you in Plane Mode, this means you can see the contribution to the picture made by each frame in turn by pressing the Up and Down Arrow keys. This mode is indicated by something like 'VFullPlane=MyFrame1'. P is again a toggle key.
Finally pressing the toggle key 'D' displays the Depthmap which shows the altitude of each pixel in the picture, blue pixels come from the bottom frame, and light greenish pixels from the top frame with intermediate colours from intermediate frames.
It is possible, and quite legal, to combine any of these viewing options thus something like 'VFixMag.PlaneDepth=picture' is OK and can be useful. Pressing Escape is a quick way of removing some of these options.
Finally A1 and A2 are abbreviations for the Active Frame and Active Frame 2. e.g. 'A1=MyFrame02' means MyFrame02 is the Active Frame.
When working with filters the Title Line format changes, most of what it shows is pretty obvious but the numbers in brackets are values entered, pressing the right and left arrows cycles through these values, the name of each one appears after the brackets. To change a value press 'V' and enter it or use 'M', 'N', and the Up and Down keys as usual.