I run ImageJ (v1.35c) on serveral PCs (WinXP SP2). On one system, the active
image window changes inadvertently (moving th mouse cursor over an image
makes this the active one, without pressing any mouse button).
In the other installations, an image window becomes the active one by
clicking onto the upper window bar, and is not changed when movimg the mouse
over anothe window. This is the desired behaviour.