Methods of and apparatus for displaying windows on a display

An apparatus for displaying windows on a display in which a window to be displayed is first written to a window buffer for storing the window when the window is generated and then written therefrom to a frame buffer for display, the apparatus comprising:

• processing circuitry configured to, when a new version of a window to be displayed is generated and stored in a window buffer for writing to the frame buffer, compare the new version of the window in the window buffer to the version of the window that was written to the frame buffer to show the window in its current form on the display;
• processing circuitry configured to use the comparison to identify regions of the window that have changed in the new version of the window;
• and
• processing circuitry configured to determine the regions of the new version of the window to write to the frame buffer in order to display the new version of the window on a display on the basis of those regions of the new version of the window that have been identified as having changed by the processing circuitry configured to use the comparison to identify regions of the window that have changed in the new version of the window.

A computer readable storage medium storing computer software code which when executing on one or more processors performs a method of displaying windows on a display in which a window to be displayed is first written to a window buffer for storing the window when the window is generated and then written therefrom to a frame buffer for display, the method comprising:

• when a new version of a window to be displayed is generated and stored in a window buffer for writing to the frame buffer:
• comparing the new version of the window in the window buffer to the version of the window that was written to the frame buffer to show the window in its current form on the display;
• using the comparison to identify regions of the window that have changed in the new version of the window;
• and
• determining the regions of the new version of the window to write to the frame buffer in order to display the new version of the window on the display on the basis of those regions of the new version of the window that have been identified as having changed using the comparison.