[Windows] Prevent right button drag

Author: r0x0r

webview/platforms/win32.py

@@ -14,6 +14,7 @@
 _SWP_NOSIZE = 0x0001
 _SWP_NOZORDER = 0x0004
 _SWP_NOACTIVATE = 0x0010
+_VK_LBUTTON = 0x01
 
 
 class _MSLLHOOKSTRUCT(ctypes.Structure):
@@ -74,6 +75,8 @@ class _MSLLHOOKSTRUCT(ctypes.Structure):
     ctypes.c_int,
     wintypes.UINT,
 ]
+_user32.GetKeyState.restype = wintypes.SHORT
+_user32.GetKeyState.argtypes = [ctypes.c_int]
 
 _LowLevelMouseProcType = ctypes.WINFUNCTYPE(
     ctypes.c_ssize_t, ctypes.c_int, wintypes.WPARAM, ctypes.c_void_p
@@ -211,6 +214,10 @@ def start_drag(hwnd: int) -> None:
     if _user32.IsZoomed(hwnd):
         return
 
+    # Only start drag if left mouse button is pressed
+    if not (_user32.GetKeyState(_VK_LBUTTON) & 0x8000):
+        return
+
     drag = _drag_states.get(hwnd)
     if drag is not None:
         rect = wintypes.RECT()