WM SYSCOMMAND

This message is posted to the queue of the owner of the control, thereby offering it the opportunity to perform some activity as a result.

For Frame Control Window Processing

This message occurs when a control window has a significant event to notify to its owner, or when a key stroke has been translated by an accelerator table into a WM_SYSCOMMAND.

In Button Control Window Processing

Button control sets uscmd to the button identity.

In Menu Control Window Processing

The menu control window procedure sets uscmd to the menu-item identity.

In Title Bar Controls

The title bar control window procedure sets uscmd to the title bar control identity and ussource to CMDSRC_OTHER.

In Default Window Procedure Message Processing

This message occurs when a control has a significant event to report to its owner or when a key stroke has been translated by an accelerator table.

Syntax

param1
     USHORT  uscmd       /*  Command value. */

param2
     USHORT  ussource    /*  Source type. */
     BOOL    fpointer    /*  Pointing-device indicator. */

Parameters

Default

uscmd (USHORT)

Command value.

The command value can be one of the SC_* values. It is the responsibility of the application to be able to relate uscmd to an application function.

ussource (USHORT)

Source type.

Identifies the type of control:

CMDSRC_PUSHBUTTON

Posted by a push-button control. uscmd is the window identifier of the push button.

CMDSRC_MENU

Posted by a menu control. uscmd is the identifier of the menu item.

CMDSRC_ACCELERATOR

Posted as the result of an accelerator. uscmd is the accelerator command value.

CMDSRC_OTHER

Other source. uscmd gives further control-specific information defined for each control type.

uspointer (USHORT)

Pointing-device indicator.

TRUE

The message is posted as a result of a pointing-device operation.

FALSE

The message is posted as a result of a keyboard operation.

For Frame Control Window Processing

uscmd (USHORT)

Command value.

The frame control takes the action described on these uscmd values:

SC_SIZE

Sends a WM_TRACKFRAME (in Frame Controls) to the frame window.

SC_MOVE

Sends a WM_TRACKFRAME (in Frame Controls) to the frame window.

SC_MINIMIZE

If a control with the identifier FID_MINMAX is present, minimizes the frame window; otherwise nothing is done.

SC_MAXIMIZE

If a control with the identifier FID_MINMAX is present, maximizes the frame window; otherwise nothing is done.

When a window is moved or sized in the normal way at least one border should remain on the screen. When a window is maximized and the maximum size is as large as the screen, all borders should be positioned just outside the screen.

SC_RESTORE

If a control with the identifier FID_MINMAX is present, restores a maximized or minimized frame window to its previous size and position; otherwise nothing is done.

SC_NEXT

Cycles the active window status to the next main window.

SC_APPMENU

Sends a MM_STARTMENUMODE message to the control with the identifier FID_MENU.

SC_SYSMENU

Sends a MM_STARTMENUMODE message to the control with the identifier FID_SYSMENU.

SC_CLOSE

If Close is not enabled in the system menu, this message is ignored. Otherwise the frame posts a WM_CLOSE message to the client if it exists or to itself, if not.

SC_NEXTFRAME

The next frame window that is a child of the desktop window is activated.

SC_NEXTWINDOW

The next window with the same owner window is activated.

SC_TASKMANAGER

The Task List is activated.

SC_HELPEXTENDED

The frame manager sends HM_EXT_HELP to the associated Help Manager Object Window. If there is no such associated window, the original message is sent to the client.

SC_HELPKEYS

The frame manager sends HM_KEYS_HELP to the associated Help Manager Object Window. If there is no such associated window, the original message is sent to the client.

SC_HELPINDEX

The frame manager sends HM_HELP_INDEX to the associated Help Manager Object Window. If there is no such associated window, the original message is sent to the client.

SC_HIDE

Sets the visibility state of the frame window to off causing it to appear hidden or invisible.

ussource (USHORT)

Source type.

Identifies the type of control:

CMDSRC_PUSHBUTTON

Posted by a push-button control: uscmd is the window identifier of the push button.

CMDSRC_MENU

Posted by a menu control: uscmd is the identifier of the menu item.

CMDSRC_ACCELERATOR

Posted as the result of an accelerator: uscmd is the accelerator command value.

CMDSRC_OTHER

Other source: uscmd gives further control-specific information defined for each control type.

fpointer (BOOL)

Pointing-device indicator.

TRUE

The message is posted as a result of a pointing-device operation.

FALSE

The message is posted as a result of a keyboard operation.

Returns

ulReserved (ULONG)

Reserved value, should be 0.

Remarks

Default

This message is posted to the queue of the owner of the control, thereby offering it the opportunity to perform some activity as a result.

For Frame Control Window Processing

This message is posted to the window procedure of the owner of the frame control. ulReserved is set to 0.

For Button Control Window Processing

If the button control is specified with a style of BS_SYSCOMMAND but not with BS_HELP, the button control generates this message and posts it to the queue of its owner when a push button is pressed, or when it receives a BM_CLICK message.

For Menu Control Window Processing

The menu control window procedure generates this message and posts it to the queue of its owner, when an item is selected that has the style of MIS_SYSCOMMAND, but only if the WM_MENUSELECT (in Menu Controls) message returns a rc of TRUE.

In Title Bar Controls

The title bar control window procedure generates this message when a mouse input message is received. The window procedure posts the message to the queue of the window owner.

The purpose of this message is to notify the owner window to maximize or restore depending on its current state.

Default Processing

The default window procedure takes no action on this message, other than to set ulReserved to 0.

Related Messages

• WM_COMMAND