Microsoft KB Archive/248655

= BUG: ATL Composite Controls Do Not Meet Windows 2000 Logo Requirement =

Article ID: 248655

Article Last Modified on 2/12/2007

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APPLIES TO


 * Microsoft Visual C++ 6.0 Enterprise Edition
 * Microsoft Visual C++ 6.0 Professional Edition
 * Microsoft Visual C++ 6.0 Standard Edition
 * Microsoft Windows 2000 Standard Edition

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This article was previously published under Q248655



SYMPTOMS
When Windows 2000 is placed into high contrast mode, the ATL Composite controls do not change their background color. Due to this behavior, any application using an ATL Composite control fails Windows 2000 logo compliancy.



CAUSE
This is due to a limitation in the ATL framework for ATL Composite controls. CComCompositeControl handles the WM_CTLCOLORDLG and WM_CTLCOLORSTATIC messages in the ATL framework and uses the container's ambient background color to paint the background and any static controls. When Windows 2000 goes into high contrast mode, the WM_CTLCOLORDLG and WM_CTLCOLORSTATIC messages are sent to the ATL Composite control. Because the control uses the ambient background color of the container when the WM_CTLCOLORDLG or WM_CTLCOLORSTATICC message is received, the messages are not passed on to DefWindowProc, and the background color and static control's color does not change.



RESOLUTION
The following modifications can be made to an ATL Composite control to allow it to pass Windows 2000 logo compliancy.   In the composite control's header file and class declaration, add message handler entries for WM_CTLCOLORDLG and WM_CTLCOLORSTATIC. It should look like the following: BEGIN_MSG_MAP(CATLCONTROLObj1) MESSAGE_HANDLER(WM_CTLCOLORDLG, OnColorDlg) MESSAGE_HANDLER(WM_CTLCOLORSTATIC, OnColorDlg) CHAIN_MSG_MAP(CComCompositeControl) END_MSG_MAP

Notice that the MESSAGE_HANDLER entries appear before the CHAIN_MSG_MAP entry. With the entries in this order, the ATL message routing architecture uses the OnColorDlg function first before using any message handlers provided for these messages by the ATL framework.   Add a new message handler function, OnColorDlg, in your ATL composite control class in the control's header file for the above to entries made to the message map. The function should have the following prototype and code inside of it: LRESULT OnColorDlg(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled) { HIGHCONTRAST highcontrast = { 0 }; highcontrast.cbSize = sizeof(HIGHCONTRAST); if (SystemParametersInfo(SPI_GETHIGHCONTRAST, sizeof(HIGHCONTRAST), &highcontrast, 0)) {     if (highcontrast.dwFlags & HCF_HIGHCONTRASTON) //high contrast on? return DefWindowProc; //Ignore ambient back color and pass to system. } //else, must be OS where SPI_GETHIGHCONTRAST not available

//Set bHandled to FALSE to allow the message to keep on being routed to base bHandled = FALSE;

return FALSE; //Let message continue to base class. }                    Save the header file and rebuild the control.

 Insert the control into Test Container and place Windows 2000 into high contrast mode. You can place Windows 2000 into high contrast mode using the following keystrokes: LEFT ALT + LEFT SHIFT + PRINT SCREEN.

Notice that the ATL Composite control's background and any static controls change color when Windows 2000 is placed into high contrast mode.



STATUS
Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article.

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Steps to Reproduce Behavior

 * 1) Create a new ATL project using the ATL COM AppWizard. Give the project the name "TestHighCotrast" and click OK.
 * 2) On the ATL COM AppWizard Step 1 of 1 screen, accept the defaults and click Finish.
 * 3) From the Insert menu, select New ATL Object.
 * 4) Click Controls under the Category section. Click Composite Control under the Objects section. Click Next.
 * 5) In the ATL Object Wizard Properties dialog box, give the short name for the control the name TestHighContrastControl. Accept the defaults for the remaining settings and click OK.
 * 6) Build the project.
 * 7) Insert the control into Test Container and place Windows 2000 into high contrast mode. You can place Windows 2000 into high contrast mode using these keystrokes: LEFT ALT + LEFT SHIFT + PRINT SCREEN.

Notice that the ATL Composite control's background and any static controls on the control do not change color when Windows 2000 is placed into high contrast mode.

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