uxtheme/tests: Add a test for OpenThemeData("explorer::treeview").

dlls/uxtheme/tests/system.c

@@ -559,6 +559,27 @@ static void test_OpenThemeData(void)
     /* Only do the next checks if we have an active theme */
 
     SetLastError(0xdeadbeef);
+    hTheme = OpenThemeData(hWnd, L"dead::beef;explorer::treeview");
+    ok(!hTheme, "OpenThemeData() should fail\n");
+    ok(GetLastError() == E_PROP_ID_UNSUPPORTED, "Got unexpected %#lx.\n", GetLastError());
+
+    SetLastError(0xdeadbeef);
+    hTheme = OpenThemeData(hWnd, L"explorer::treeview");
+    todo_wine
+    ok(hTheme != NULL, "OpenThemeData() failed\n");
+    todo_wine
+    ok(GetLastError() == ERROR_SUCCESS, "Expected ERROR_SUCCESS, got 0x%08lx\n", GetLastError());
+    CloseThemeData(hTheme);
+
+    SetLastError(0xdeadbeef);
+    hTheme = OpenThemeData(hWnd, L"deadbeef::treeview;dead::beef");
+    todo_wine
+    ok(hTheme != NULL, "OpenThemeData() failed\n");
+    todo_wine
+    ok(GetLastError() == ERROR_SUCCESS, "Expected ERROR_SUCCESS, got 0x%08lx\n", GetLastError());
+    CloseThemeData(hTheme);
+
+    SetLastError(0xdeadbeef);
     hTheme = OpenThemeData(hWnd, szButtonClassList);
     ok( hTheme != NULL, "got NULL, expected a HTHEME handle\n");
     ok( GetLastError() == ERROR_SUCCESS, "Expected ERROR_SUCCESS, got 0x%08lx\n", GetLastError() );