Take disabled windows into account in wxFindWindowAtPoint() in wxMSW.

Use ChildWindowFromPointEx(CWP_SKIPINVISIBLE) to ensure that we find the
disabled children (by not using CWP_SKIPDISABLED).

Add a unit test to check for the correct behaviour in all cases and document
it.

Closes #2942.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70794 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/utils.h

@@ -404,6 +404,9 @@ void wxEnableTopLevelWindows(bool enable = true);
     Find the deepest window at the given mouse position in screen coordinates,
     returning the window if found, or @NULL if not.
 
+    This function takes child windows at the given position into account even
+    if they are disabled. The hidden children are however skipped by it.
+
     @header{wx/utils.h}
 */
 wxWindow* wxFindWindowAtPoint(const wxPoint& pt);

src/msw/window.cpp

@@ -7205,6 +7205,14 @@ wxWindow* wxFindWindowAtPoint(const wxPoint& pt)
     pt2.y = pt.y;
 
     HWND hWnd = ::WindowFromPoint(pt2);
+    if ( hWnd )
+    {
+        // WindowFromPoint() ignores the disabled children but we're supposed
+        // to take them into account, so check if we have a child at this
+        // coordinate.
+        ::ScreenToClient(hWnd, &pt2);
+        hWnd = ::ChildWindowFromPointEx(hWnd, pt2, CWP_SKIPINVISIBLE);
+    }
 
     return wxGetWindowFromHWND((WXHWND)hWnd);
 }

tests/misc/guifuncs.cpp

@@ -17,12 +17,15 @@
     #pragma hdrstop
 #endif
 
+#include "wx/defs.h"
+
 #ifndef WX_PRECOMP
     #include "wx/gdicmn.h"
     #include "wx/filefn.h"
 #endif // !PCH
 
-#include "wx/defs.h"
+#include "wx/app.h"
+#include "wx/button.h"
 #include "wx/clipbrd.h"
 #include "wx/dataobj.h"
 
@@ -40,11 +43,13 @@ private:
         CPPUNIT_TEST( DisplaySize );
         CPPUNIT_TEST( URLDataObject );
         CPPUNIT_TEST( ParseFileDialogFilter );
+        CPPUNIT_TEST( FindWindowAtPoint );
     CPPUNIT_TEST_SUITE_END();
 
     void DisplaySize();
     void URLDataObject();
     void ParseFileDialogFilter();
+    void FindWindowAtPoint();
 
     DECLARE_NO_COPY_CLASS(MiscGUIFuncsTestCase)
 };
@@ -129,3 +134,46 @@ void MiscGUIFuncsTestCase::ParseFileDialogFilter()
     );
 }
 
+void MiscGUIFuncsTestCase::FindWindowAtPoint()
+{
+    wxWindow* const parent = wxTheApp->GetTopWindow();
+    CPPUNIT_ASSERT( parent );
+
+    CPPUNIT_ASSERT_MESSAGE
+    (
+        "No window for a point outside of the window",
+        !wxFindWindowAtPoint(parent->ClientToScreen(wxPoint(900, 900)))
+    );
+
+    wxWindow* const btn1 = new wxButton(parent, wxID_ANY, "1", wxPoint(10, 10));
+    CPPUNIT_ASSERT_EQUAL_MESSAGE
+    (
+        "Point over a child control corresponds to it",
+        btn1,
+        wxFindWindowAtPoint(parent->ClientToScreen(wxPoint(11, 11)))
+    );
+
+    CPPUNIT_ASSERT_EQUAL_MESSAGE
+    (
+        "Point outside of any child control returns the TLW itself",
+        parent,
+        wxFindWindowAtPoint(parent->ClientToScreen(wxPoint(5, 5)))
+    );
+
+    wxWindow* const btn2 = new wxButton(parent, wxID_ANY, "2", wxPoint(10, 90));
+    btn2->Disable();
+    CPPUNIT_ASSERT_EQUAL_MESSAGE
+    (
+        "Point over a disabled child control still corresponds to it",
+        btn2,
+        wxFindWindowAtPoint(parent->ClientToScreen(wxPoint(11, 91)))
+    );
+
+    btn2->Hide();
+    CPPUNIT_ASSERT_EQUAL_MESSAGE
+    (
+        "Point over a hidden child control doesn't take it into account",
+        parent,
+        wxFindWindowAtPoint(parent->ClientToScreen(wxPoint(11, 91)))
+    );
+}