To match window size with the size of the model:
Click Zoom to Fit toolbar button.
To magnify the picture:
Click Zoom In toolbar button.
With left button pressed drag the mouse diagonally to draw a rubberband rectangle around that part of the model you want to fill the window, and release the button.
OrClick inside the window. QuickField will use magnification factor 2 relative to the clicked point.
Shortcut: CTRL + emulates click at the central point of the window.
To see more of the model:
Click Zoom Out toolbar button.
Shortcut: CTRL -
Several Zoom Ins followed by the same number of Zoom Outs applied to the same model window leave the window in the same state as before.
Related Topics:
Control Picture in a 3D View
Zooming the Field Picture