Open the system menu when user right clicks the drag bar

.github/actions/spell-check/dictionary/apis.txt

@@ -24,6 +24,7 @@ NOAGGREGATION
 NOREDIRECTIONBITMAP
 oaidl
 ocidl
+RETURNCMD
 rfind
 roundf
 SIZENS

src/cascadia/WindowsTerminal/NonClientIslandWindow.cpp

@@ -124,10 +124,11 @@ LRESULT NonClientIslandWindow::_InputSinkMessageHandler(UINT const message, WPAR
  {
  auto parentWindow{ GetWindowHandle() };
 
+ const LPARAM newLparam = MAKELPARAM(screenPt.x, screenPt.y);
  // Hit test the parent window at the screen coordinates the user clicked in the drag input sink window,
  // then pass that click through as an NC click in that location.
- const LRESULT hitTest{ SendMessage(parentWindow, WM_NCHITTEST, 0, MAKELPARAM(screenPt.x, screenPt.y)) };
- SendMessage(parentWindow, nonClientMessage.value(), hitTest, 0);
+ const LRESULT hitTest{ SendMessage(parentWindow, WM_NCHITTEST, 0, newLparam) };
+ SendMessage(parentWindow, nonClientMessage.value(), hitTest, newLparam);
 
  return 0;
  }
@@ -691,6 +692,14 @@ void NonClientIslandWindow::_UpdateFrameMargins() const noexcept
  return _OnNcHitTest({ GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam) });
  case WM_PAINT:
  return _OnPaint();
+ case WM_NCRBUTTONUP:
+ // The `DefWindowProc` function doesn't open the system menu for some
+ // reason so we have to do it ourselves.
+ if (wParam == HTCAPTION)
+ {
+ _OpenSystemMenu(GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam));
+ }
+ break;
  }
 
  return IslandWindow::MessageHandler(message, wParam, lParam);
@@ -862,3 +871,47 @@ bool NonClientIslandWindow::_IsTitlebarVisible() const
  // updated to include that mode.
  return !_fullscreen;
 }
+
+// Method Description:
+// - Opens the window's system menu.
+// - The system menu is the menu that opens when the user presses Alt+Space or
+// right clicks on the title bar.
+// - Before updating the menu, we update the buttons like "Maximize" and
+// "Restore" so that they are grayed out depending on the window's state.
+// Arguments:
+// - cursorX: the cursor's X position in screen coordinates
+// - cursorY: the cursor's Y position in screen coordinates
+void NonClientIslandWindow::_OpenSystemMenu(const int cursorX, const int cursorY) const noexcept
+{
+ const auto systemMenu = GetSystemMenu(_window.get(), FALSE);
+
+ WINDOWPLACEMENT placement;
+ if (!GetWindowPlacement(_window.get(), &placement))
+ {
+ return;
+ }
+ const bool isMaximized = placement.showCmd == SW_SHOWMAXIMIZED;
+
+ // Update the options based on window state.
+ MENUITEMINFO mii;
+ mii.cbSize = sizeof(MENUITEMINFO);
+ mii.fMask = MIIM_STATE;
+ mii.fType = MFT_STRING;
+ auto setState = [&](UINT item, bool enabled) {
+ mii.fState = enabled ? MF_ENABLED : MF_DISABLED;
+ SetMenuItemInfo(systemMenu, item, FALSE, &mii);
+ };
+ setState(SC_RESTORE, isMaximized);
+ setState(SC_MOVE, !isMaximized);
+ setState(SC_SIZE, !isMaximized);
+ setState(SC_MINIMIZE, true);
+ setState(SC_MAXIMIZE, !isMaximized);
+ setState(SC_CLOSE, true);
+ SetMenuDefaultItem(systemMenu, UINT_MAX, FALSE);
+
+ const auto ret = TrackPopupMenu(systemMenu, TPM_RETURNCMD, cursorX, cursorY, 0, _window.get(), nullptr);
+ if (ret != 0)
+ {
+ PostMessage(_window.get(), WM_SYSCOMMAND, ret, 0);
+ }
+}

src/cascadia/WindowsTerminal/NonClientIslandWindow.h

@@ -86,4 +86,6 @@ class NonClientIslandWindow : public IslandWindow
  void _UpdateMaximizedState();
  void _UpdateIslandPosition(const UINT windowWidth, const UINT windowHeight);
  void _UpdateFrameTheme() const;
+
+ void _OpenSystemMenu(const int mouseX, const int mouseY) const noexcept;
 };