By default GIMP has a checkerboard pattern built up of mid-tone gray checks. You can, however, change that in the drop down menu.
![]() | The white, black and gray only options disable checks and the transparency will be shown as a solid black, white, or gray color. |
Sets the size of the checks in the pattern that indicates transparency.
![]() | If you have set the check type to white, gray, or black only, then the size will have no effect what so ever. |
If you are working on an 8-Bit display, the GdkRGB subsystem of GDK will automatically figure out if it needs to install its own colormap or not. Since GIMP's plug-ins are all separate processes with their own instances of GdkRGB, it may happen that GIMP and some of its Plug-Ins choose different colormaps, resulting in color flickering.
If you encounter such behaviour, you can activate "Install Colormap" in order to force GIMP and its plug-ins to use the same colormap.
If you are working on an 8-Bit display, you can display the "Marching Ants" which show the current selection by means of a rotating colormap instead of re-drawing them all the time.