Figure 5-35 Scrolling by clicking in the gray area Pressing in the gray area causes the display of consecutive windowfuls of the document, until the user releases the mouse button, or until the location of the scroll box catches up to the location of the pointer. A windowful equals the height or width of the window, minus at least one unit of overlap to maintain the user's context. This unit of overlap is the same measurement determined for scroll arrow movement. By retaining this unit of information, you provide a reference point for the user.
On keyboards with function keys, the Page Up and Page Down keys also move the document view by a windowful.
Figure 5-36 Scrolling by dragging the scroll box
Figure 5-35 Scrolling by clicking in the gray area Pressing in the gray area causes the display of consecutive windowfuls of the document, until the user releases the mouse button, or until the location of the scroll box catches up to the location of the pointer. A windowful equals the height or width of the window, minus at least one unit of overlap to maintain the user's context. This unit of overlap is the same measurement determined for scroll arrow movement. By retaining this unit of information, you provide a reference point for the user.
On keyboards with function keys, the Page Up and Page Down keys also move the document view by a windowful.