Only primary windows, not secondary windows, should include an entry on the taskbar.
When the user opens a primary window, include an entry for it on the taskbar. If the window has been opened previously, restore the window to its size and position when it was last closed. If possible and appropriate, reinstate the other related view information, such as selection state, scroll position, and type of view. When opening a primary window for the first time, open it to a reasonable default size and position as best defined by the object or application. For details about storing state information in the system registry, see Chapter 10, "Integrating with the System."
Note
Only primary windows, not secondary windows, should include an entry on the taskbar.
Because display resolution and orientation varies, your software should not assume a fixed display size, but rather adapt to the shape and size defined by the system. If you use standard system interfaces the system automatically places your windows relative to the current display configuration.
Note 
The SetWindow-Placement function is an example of a system interface that will automatically place windows correctly relative to the current display. For more information about this function, see the documentation included in the Win32 SDK.
Opening the primary window activates that window and places it at the top of the window order. If the use attempts to open a primary window that is already open within the same desktop, activate the existing window using the following recommendations. If the existing window is minimized, restore it when you activate it.
|
File type |
Action when repeating an Open operation |
|
Document or data file |
Activates the existing window of the object and displays it at the top of the window Z order. |
|
Application file |
Displays a message box indicating that an open window of that application already exists and offers the user the option to switch to the open window or to open another window. Either choice activates the selected window and brings it to the top of the window Z order. |
|
Document file that is already open in an MDI application window |
Activates the existing window of the file. Its MDI parent window comes to the top of the window Z order, and the file appears at the top of the Z order within its MDI parent window. |
|
Document file that is not already open, but its associated MDI application is already running (open) |
Opens a new instance of the file's associated MDI application at the top of the window Z order and displays the child window for the file. Optionally, as an alternative, displays a message box indicating that an open window of that application already exists and offers the user the option to use the existing window or to open a new parent window. |
Note
For more information about MDI, see Chapter 9, "Window Management."
The user closes a primary window by clicking (for a pen, tapping the screen) the Close button in the title bar or choosing the Close command from the window's pop-up menu. Although the system supports double-clicking (with a pen, double-tapping the screen) on the title bar icon as a shortcut for closing the window for compatibility with previous versions of Windows, avoid documenting this as the primary way to close a primary window. Instead, document the Close button.
When the user chooses the Close command, if your application does not automatically save these changes and pending transactions or edits that have not yet been saved to file remain, display a message asking the user whether to save any changes, discard any changes, or cancel the Close operation before closing the window. If there are no pending transactions, just close the window. Follow this same convention for any other command that results in closing the primary window (for example, Exit or Shut Down).
Note
For more information about supporting the Close command, see Chapter 5, "General Interaction Techniques."
When closing the primary window, close any of its dependent secondary windows as well. The design of your application determines whether closing the primary window also ends the application processes. For example, closing the window of a text document typically halts any application code or processes remaining for inputting or formatting text. However, closing the window of a printer has no effect on the jobs in the printer's queue. In both cases, closing the window removes its entry from the taskbar.