Make your primary windows resizable unless the information displayed in the window is fixed, such as in the Windows Calculator program. The system provides several conventions that support user resizing of a window.
The user resizes a primary window by dragging the sizing border with the mouse or pen at the edge of a window or by using the Size command on the window's menu. An outline representation of the window moves with the pointer. (On some configurations, the system may include a display option to dynamically redraw the window as it is sized.) After completing the size operation, the window assumes its new size. Using the keyboard, the user can size the window by choosing the Size command, using the arrow keys, and pressing the ENTER key.
A window does not need to be active before the user can resize it. The action of sizing the window implicitly makes it active, and it remains active after the sizing operation.
When the user resizes a window to be smaller, you must determine how to display the information viewed in that window. Use the context and type of information to help you choose your approach. The most common approach is to clip the information. However, in other situations where you want the user to see as much information as possible, you may want to consider using different methods, such as rewrapping or scaling the information. Use these variations carefully because they may not be consistent with the resizing behavior of most windows. In addition, avoid these methods when readability or maintaining the structural relationship of the information is important.
Although the size of a primary window can vary, based on the user's preference, you can define a window's maximum size. When defining this size, consider the reasonable usage within the window, and the size and orientation of the screen.
Although the user may be able to directly resize a window to its maximum size, the Maximize command optimizes this operation. Include this command on a window's pop-up menu, and as the Maximize command button in the title bar of the window.
Maximizing a window increases the size of the window to its largest, optimum size. The system default setting for the maximum size is as large as the display, excluding the space used by the taskbar (or other application-defined desktop toolbars). For an MDI child window, the default maximize size fills the parent window. But, you can define the size to be less or, in some cases, more than the default dimensions.
When the user maximizes a window, replace the Maximize button with a Restore button. Then, disable the Maximize command and enable the Restore command on the pop-up menu for the window.
Minimizing a window reduces it to its smallest size. To support this command, include it on the pop-up menu for the window and as the Minimize command button in the title bar of the window.
For primary windows, minimizing removes the window from the screen, but leaves its entry in the taskbar. For MDI child windows, the window resizes to a minimum size within its parent window. To minimize a window, the user chooses the Minimize command from the window's pop-up menu or the Minimize command button on the title bar.
Note 
Because the representation of minimized windows changed in Microsoft Windows 95, using an icon as the way to reflect state information may not be appropriate. As an alternative, you may want to consider creating a status indicator for the taskbar. For more information about status notification, see Chapter 10, "Integrating with the System."
When the user minimizes a window, disable the Minimize command on the pop-up menu and enable the Restore command.
Support the Restore command to restore a window to its previous size and position after the user has maximized or minimized the window. For maximized windows, enable this command on the window's pop-up menu and replace the Maximize button with the Restore button in the title bar of the window.
For minimized windows, also enable the Restore command in the pop-up menu of the window. The user restores a minimized primary window to its former size and position by clicking (for pens, tapping the screen) on its button in the taskbar that represents the window, selecting the Restore command on the pop-up menu of the window's taskbar button, or using the ALT+TAB (or the SHIFT+ALT+TAB) key combination.
When you define a sizable window, you may include a size grip. A size grip is a special handle for sizing a window. It is not exclusive to the sizing border. To size the window, the user drags the grip and the window resizes following the same conventions as the sizing border.
Always locate the size grip in the lower right corner of the window. Typically, this means you place the size grip at the right end of a horizontal scroll bar or the bottom of a vertical scroll bar. However, if you include a status bar in the window, display the size grip at the far corner of the status bar instead. Never display the size grip in both locations at the same time.
Note 
For more information about the use of the size grip in a status bar, see Chapter 7, "Menus, Controls, and Toolbars."