Zhiyi Zhang (@zhiyi) commented about dlls/comctl32/tests/button.c:
/* Test already focused button */
button = create_button(types[i] | WS_VISIBLE, hwnd);
SendMessageA(button, WM_SETFOCUS, 0, 0);
SendMessageA(button, BM_SETCHECK, BST_UNCHECKED, 0);
while (PeekMessageA(&msg, 0, 0, 0, PM_REMOVE)) DispatchMessageA(&msg);
flush_sequences(sequences, NUM_MSG_SEQUENCES);
SendMessageA(button, WM_SETFOCUS, 0, 0);
while (PeekMessageA(&msg, 0, 0, 0, PM_REMOVE)) DispatchMessageA(&msg);
ok_sequence(sequences, COMBINED_SEQ_INDEX, set_focus_default_seq, "WM_SETFOCUS on focused radiobutton", TRUE);
DestroyWindow(button);
/* Test WM_LBUTTONDOWN */
button = create_button(types[i] | WS_VISIBLE, hwnd);
while (PeekMessageA(&msg, 0, 0, 0, PM_REMOVE)) DispatchMessageA(&msg);
flush_sequences(sequences, NUM_MSG_SEQUENCES);
SendMessageA(button, WM_LBUTTONDOWN, 0, 0);
Let's use non-zero coordinates for LPARAM just in case Windows checks the message coordinates. I did try MAKELPARAM(7, 7) and it does have the same message sequence on Windows 10.