MSFlexGrid UIAutomation C++ API

Hello, 

I am building a Test Automation Tool for testing an old VB6 Windows Desktop application containing instances of MSFlexGrid. I am using the Client UIAutomation C++ API on Windows 7 and Visual Studio 2015.

The VB6 target application does not implement any Server UIAutomation feature. Despite that, I can successfully communicate with UI components (like Text field, Combo box, Check box) and I can get and set values on them.

But, I could not find any way to manage MSFlexGrid (i.e., reading the content of the grid). These are the details for an instance of MSFlexGrid from the Inspect tool:

************************************************************************************

hwnd=0x00000000000609AA 32bit class="MSFlexGridWndClass" style=0x54B00000 ex=0x200
RuntimeId:"[42.395690]"
BoundingRectangle:{l:572 t:251 r:1360 b:651}
ProcessId:4492
ControlType:UIA_PaneControlTypeId (0xC371)
LocalizedControlType:"pane"
Name:""
AccessKey:""
HasKeyboardFocus:true
IsKeyboardFocusable:true
IsEnabled:true
ClassName:"MSFlexGridWndClass"
HelpText:""
IsPassword:false
NativeWindowHandle:0x609AA
IsOffscreen:false
FrameworkId:"Win32"
ProviderDescription:"[pid:14012,hwnd:0x609AA Main:Nested [pid:4492,hwnd:0x609AA Annotation(parent link):Microsoft: Annotation Proxy (unmanaged:uiautomationcore.dll); Main:Microsoft: MSAA Proxy (unmanaged:uiautomationcore.dll)]; Nonclient:Microsoft: Non-Client Proxy (unmanaged:uiautomationcore.dll); Hwnd(parent link):Microsoft: HWND Proxy (unmanaged:uiautomationcore.dll)]"
Scroll.HorizontalScrollPercent:0.000000
Scroll.HorizontalViewSize:50.000000
Scroll.VerticalScrollPercent:66.666667
Scroll.VerticalViewSize:14.285714
Scroll.HorizontallyScrollable:true
Scroll.VerticallyScrollable:true
IsDockPatternAvailable:false
IsExpandCollapsePatternAvailable:false
IsGridItemPatternAvailable:false
IsGridPatternAvailable:false
IsInvokePatternAvailable:false
IsMultipleViewPatternAvailable:false
IsRangeValuePatternAvailable:false
IsScrollPatternAvailable:true
IsScrollItemPatternAvailable:false
IsSelectionItemPatternAvailable:false
IsSelectionPatternAvailable:false
IsTablePatternAvailable:false
IsTableItemPatternAvailable:false
IsTextPatternAvailable:false
IsTogglePatternAvailable:false
IsTransformPatternAvailable:false
IsValuePatternAvailable:false
IsWindowPatternAvailable:false
IsItemContainerPatternAvailable:false
IsVirtualizedItemPatternAvailable:false
FirstChild:"Vertical" scroll bar
LastChild:(null) thumb
Next:[null]
Previous:"" pane
Other Props:Object has no additional properties
Children:"Vertical" scroll bar
"Horizontal" scroll bar

************************************************************************************

As you can see, the Scroll Pattern is the only one available. 

I tried to use the Win32 SendMessage(gridHWND, ..) function to communicate directly with the MSFlexGrid, with no results. 

I also tried to model my Test Automation Tool as a MFC project, so that I could use the CMSFlexGrid code generated by Visual Studio when I add the MSFlexGrid ActiveX component to the project. What I tried is something like:

CMSFlexGrid grid;
grid.Attach(target_MSFLEXGRID_HWND);
long rows = grid.get_Rows();

No results again, I get an assertion error in winocc.cpp in the CWnd::InvokeHelper():

/////////////////////////////////////////////////////////////////////////////
// CWnd invoke helpers for OLE Control wrappers

void AFX_CDECL CWnd::InvokeHelper(DISPID dwDispID, WORD wFlags, VARTYPE vtRet,
	void* pvRet, const BYTE* pbParamInfo, ...)
{
	ASSERT(m_pCtrlSite != NULL);    // not an OLE control (not yet, at least)

	if (m_pCtrlSite == NULL)
		return;

	va_list argList;
	va_start(argList, pbParamInfo);
	m_pCtrlSite->InvokeHelperV(dwDispID, wFlags, vtRet, pvRet, pbParamInfo,
		argList);
	va_end(argList);
}

Does anybody know if I there is a way to read the content of a MSFlexGrid living in another process?

Many thanks in advance