What is Colormap Flashing?
The default colormap which is created when OpenWindows is invoked has a fixed number of elements, normally 256. This means that up to 256 different colours can be allocated (note that not all will necessarily be visible at the time). If an application attempts to allocate a new colour and there is no space in the colormap, it will get an error returned from the server. At this point the application has two alternatives: to accept the limitation and use only those colours which are already defined, or to create a new colormap for its sole use. Assuming that the latter approach is taken, whenever the user moves the mouse cursor over the application window the server will automatically switch in the custom colormap to replace the default. In doing so, the colours of various items and windows may well be affected. In some cases other windows may become illegible, due to odd combinations of foreground and background colours – making it difficult to view multiple windows simultaneously.
