INFO: Value Returned by GetWindowLong(hWnd, GWL_STYLE)

• Microsoft Win32 Software Development Kit (SDK), on platform(s):
  • Microsoft Windows NT, versions 3.5, 3.51
  • Microsoft Windows 95
  • Microsoft Windows Software Development Kit (SDK) 3.1

SUMMARY

GetWindowLong(hWnd, GWL_STYLE) returns the window style information stored at the GWL_STYLE offset of the window data structure identified by hWnd. This offset contains the current state of the window, rather than the style specified when the window was created.

Windows can set and clear the following styles over the lifetime of a window: WS_CLIPSIBLINGS, WS_DISABLED, WS_HSCROLL, WS_MAXIMIZE, WS_MINIMIZE, WS_SYSMENU (for MDI child windows), WS_THICKFRAME, WS_VISIBLE, and WS_VSCROLL. Windows will not dynamically set or clear any of the other styles. An application can modify the style state at the GWL_STYLE offset at any time by calling SetWindowLong(hWnd, GWL_STYLE, dwNewLong), but Windows will not be aware that the style has changed. Windows maintains some internal flags on the window style and may use these rather than checking the GWL_STYLE offset of the window data structure.

GetWindowLong(hWnd, GWL_STYLE) returns a LONG value, which contains the currently active styles combined by the Boolean OR operator. An application can change the information stored at the GWL_STYLE offset by calling SetWindowLong(hWnd, GWL_STYLE, dwNewLong).

MORE INFORMATION

The following table lists the windows styles that Windows updates throughout the life span of a window. In the Change column below, an "S" indicates that the style is set and a "C" indicates that the style is cleared. The Where column lists the source module involved. Windows will change a window's styles as follows:

   Style       Change  Window      Where       Why
   ------------------------------------------------------------------------
   WS_CLIPSIBLINGS

               S       Overlapped  WMCREATE.C  Set on creation.

   WS_CLIPSIBLINGS

               S       Popup       WMCREATE.C  Set on creation.

   WS_DISABLED S & C   Any         WMACT.C     Set or cleared when
                                               EnableWindow function
                                               disables or enables
                                               window.

   WS_HSCROLL  S & C   SB_HORZ     WINSBCTL.C  Set or cleared as scroll
                                               bar range changed (for
                                               window scroll bar, not the
                                               SCROLL BAR class).

   WS_HSCROLL  S & C   SB_HORZ     SBRARE.C    Set or cleared in
                                               ShowScrollBar (for window
                                               scroll bar, not the SCROLL
                                               BAR class).

   WS_HSCROLL  S & C   List boxes  LBOXCTL1.C  Set if scroll bar required
                                               to see contents.

   WS_HSCROLL  S & C   MDI frame   MDIWIN.C    Set if required to see
                                               children.

   WS_MAXIMIZE C       Any         WMCREATE.C  On creation (reset
                                               immediately in
                                               WMMINMAX.C).

   WS_MAXIMIZE C       Any         WMMOVE.C    Cleared if window resized.

   WS_MAXIMIZE S & C   Any         WMMINMAX.C  Set if window maximized,
                                               cleared if no longer
                                               maximized.

   WS_MINIMIZE C       Any         WMCREATE.C  On creation (reset
                                               immediately in
                                               WMMINMAX.C).

   WS_MINIMIZE C       Any         WMMOVE.C    Cleared if window resized.

   WS_MINIMIZE S & C   any         WMMINMAX.C  Set if window minimized,
                                               cleared if no longer
                                               minimized.

   WS_SYSMENU  S & C   MDI child   MDIMENU.C   Cleared if child is
                                               maximized and uses frame
                                               menu. Set when child no
                                               longer maximized.
   WS_THICKFRAME
               S & C   Any         WINSBCTL.C  State changed for only a
                                               few instructions during
                                               painting.

   WS_VISIBLE  C       Any         WMCREATE.C  Cleared and then reset by
                                               call to ShowWindow.

   WS_VISIBLE  S & C   Any         WMSHOW.C    Cleared if window hidden
                                               in ShowWindow, set if
                                               shown.

   WS_VISIBLE  S & C   Any         WMSWP.C     Cleared if window hidden
                                               in ShowWindow, set if
                                               shown.

   WS_VISIBLE  C       MDI client  MDIWIN.C    Cleared when current MDI
                                               child is maximized, and
                                               new child is activated.
                                               Immediately reset with
                                               call to ShowWindow.

   WS_VISIBLE  S       Desktop     INLOADW.C   Ensure desktop visible.

   WS_VISIBLE  S & C   Any         MSDWP.C     Set or cleared when
                                               DefWindowProc receives
                                               WM_SETREDRAW message to
                                               turn drawing on or off,
                                               respectively.

   WS_VISIBLE  S & C   MDI client  MDIWIN.C    Cleared and then
                                               immediately reset to
                                               optimize painting.

   WS_VSCROLL  S & C   SB_VERT     WINSBCTL.C  Set or cleared as scroll
                                               bar range changed (for
                                               window scroll bar, not the
                                               SCROLL BAR class).

   WS_VSCROLL  S & C   List boxes  LBOXCTL1.C  Set if scroll bar required
                                               to see entire contents.

   WS_VSCROLL  S & C   MDI frame   MDIWIN.C    Set if required to see
                                               children.

   WS_VSCROLL  S & C   SB_VERT     SBRARE.C    Set/cleared in
                                               ShowScrollBar (for window
                                               scroll bar, not the SCROLL
                                               BAR class). 

• Combo boxes always report the following styles as clear:
  
  CBS_HASSTRINGS, CBS_SORT, WS_BORDER, WS_HSCROLL, and WS_VSCROLL



• All edit controls report the WS_BORDER style clear.

• Multiline edit controls report the WS_HSCROLL style clear if the control contains centered or right-justified text.

Keywords          : kbNTOS350 kbNTOS351 kbGrpUser kbWinOS310 kbWinOS95 kbWndw kbWndwProp kbWinOS300 
Version           : 
Platform          : 
Issue type        : kbinfo 

Last Reviewed: March 7, 1999