Window Hierarchy

X uses a hierarchical, or tree structure to organize its windows. A root window, occupying the entire screen, is created by the server for each screen under its control. The root window is the top of the tree, all other windows are descendants of the root. Consider a window with a label box, scroll bar and scroll thumb, such as window 1 in figure 5. This window has the root window for its parent, and has two child windows, the label box and the scroll bar. The scroll thumb window is a child of the scroll bar window. Figure 6 shows the window hierarchy for the windows in figure 5.

 
Figure 6: Window hierarchy for figure 5