From Thomas Michanek;
The window is probably "displayed" off the screen, due to a change in screen resolution.
Three solutions:
1. When you click the "display structure view" button, immediately press Alt+Spacebar followed by "M", and then hit the left or up arrow keys (don't move the mouse) until the windows starts appearing.
This will move the active window by using the keyboard arrow keys. If the wrong window is moved, press Esc and try using Ctrl+Tab or Alt+Tab to make FM select the (invisible) structure view window. (I don't have FM running so I don't know if that will work)
2. Close FM and open the maker.ini file in the FM installation folder. Scroll down to "[StructureView]" and change the line "Position=..." to some reasonable numbers, e.g. "Position=0, 0, 376, 272" (the order is X, Y, width, height in pixels, I think)
Then restart FM and try again.
3. Temporarily increase your screen resolution to its maximum, open the structure view window, move it to a better place, and change the screen resolution back.