Adds ExpandColapse pattern to SplitButton

Author: Ricardo Bossan (BEYONDSOFT CONSULTING INC) (from Dev Box)

src/System.Windows.Forms/System/Windows/Forms/Controls/ToolStrips/ToolStripSplitButton.ToolStripSplitButtonExAccessibleObject.cs

@@ -24,9 +24,10 @@ internal override VARIANT GetPropertyValue(UIA_PROPERTY_ID propertyID) =>
                 // If we don't set a default role for the accessible object
                 // it will be retrieved from Windows.
                 // And we don't have a 100% guarantee it will be correct, hence set it ourselves.
+                // SplitButton control type requires ExpandCollapse pattern support.
                 UIA_PROPERTY_ID.UIA_ControlTypePropertyId when
                     _owningToolStripSplitButton.AccessibleRole == AccessibleRole.Default
-                    => (VARIANT)(int)UIA_CONTROLTYPE_ID.UIA_ButtonControlTypeId,
+                    => (VARIANT)(int)UIA_CONTROLTYPE_ID.UIA_SplitButtonControlTypeId,
                 _ => base.GetPropertyValue(propertyID)
             };
 

src/test/unit/System.Windows.Forms/System/Windows/Forms/AccessibleObjects/ToolStripSplitButton.ToolStripSplitButtonAccessibleObjectTests.cs

@@ -20,14 +20,14 @@ public void ToolStripSplitButtonAccessibleObject_Ctor_Default()
     }
 
     [WinFormsFact]
-    public void ToolStripSplitButtonAccessibleObject_ControlType_IsButton_IfAccessibleRoleIsDefault()
+    public void ToolStripSplitButtonAccessibleObject_ControlType_IsSplitButton_IfAccessibleRoleIsDefault()
     {
         using ToolStripSplitButton toolStripSplitButton = new();
         // AccessibleRole is not set = Default
 
         var actual = (UIA_CONTROLTYPE_ID)(int)toolStripSplitButton.AccessibilityObject.GetPropertyValue(UIA_PROPERTY_ID.UIA_ControlTypePropertyId);
 
-        Assert.Equal(UIA_CONTROLTYPE_ID.UIA_ButtonControlTypeId, actual);
+        Assert.Equal(UIA_CONTROLTYPE_ID.UIA_SplitButtonControlTypeId, actual);
     }
 
     [WinFormsFact]

src/test/unit/System.Windows.Forms/System/Windows/Forms/AccessibleObjects/ToolStripSplitButton.ToolStripSplitButtonExAccessibleObjectTests.cs

@@ -23,7 +23,7 @@ public void ToolStripSplitButtonExAccessibleObject_ControlType_ReturnsExpected()
 
         ToolStripSplitButtonExAccessibleObject accessibleObject = new(toolStripSplitButton);
 
-        Assert.Equal(UIA_CONTROLTYPE_ID.UIA_ButtonControlTypeId, (UIA_CONTROLTYPE_ID)(int)accessibleObject.GetPropertyValue(UIA_PROPERTY_ID.UIA_ControlTypePropertyId));
+        Assert.Equal(UIA_CONTROLTYPE_ID.UIA_SplitButtonControlTypeId, (UIA_CONTROLTYPE_ID)(int)accessibleObject.GetPropertyValue(UIA_PROPERTY_ID.UIA_ControlTypePropertyId));
     }
 
     [WinFormsFact]