[fix] support selective mouse button release across desktop platforms

apps/harmony/native/input.cpp

@@ -111,12 +111,17 @@ bool Input::Apply(const RemoteAction& action) {
 bool Input::Release() {
   for (const auto& change : ReconcileKeyboardState(keys_, {}))
     Key({change.key_code, change.scan_code, change.extended}, false);
-  for (int button = 0; button < 3; ++button)
-    if (buttons_ & (1u << button)) Pointer(2 + button * 2, x_, y_, 0);
+  ReleaseMouseButtons(7);
   // Failed releases remain pending so a later cleanup can retry them.
   have_key_sequence_ = false;
   return keys_.empty() && buttons_ == 0;
 }
+unsigned Input::ReleaseMouseButtons(unsigned mask) {
+  mask &= 7;
+  for (int button = 0; button < 3; ++button)
+    if (buttons_ & mask & (1u << button)) Pointer(2 + button * 2, x_, y_, 0);
+  return mask & ~buttons_;
+}
 bool Input::LockWorkstation() {
   // The public Harmony shortcut is Meta+L. Never carry a prior remote drag or
   // modifier into it, and retain failed releases for the normal cleanup path.

apps/harmony/native/input.h

@@ -16,6 +16,7 @@ class Input {
   bool Configure(int width, int height, int display);
   bool Apply(const RemoteAction& action);
   bool Release();
+  unsigned ReleaseMouseButtons(unsigned mask);
   bool LockWorkstation();
  private:
   bool Key(const KeyboardKey& key, bool down);