Fix possible no-GUI state when using systray

Fixes possible Notepad++ non-GUI state when minimized to systray with an unsaved file, closing from the systray icon & then cancelling that closing from the invoked Notepad++ save dialog.

Fix #14777, close #14778

PowerEditor/src/NppBigSwitch.cpp

@@ -2595,6 +2595,15 @@ LRESULT Notepad_plus::process(HWND hwnd, UINT message, WPARAM wParam, LPARAM lPa
 					_pluginsManager.notify(&scnN);
 					if (isSnapshotMode)
 						::LockWindowUpdate(NULL);
+
+					if (!::IsWindowVisible(hwnd))
+					{
+						// Notepad++ probably has not been restored from the systray
+						// - as its tray-icon was removed before, we have to show the app window otherwise we end up with no-GUI state
+						::ShowWindow(hwnd, SW_SHOW);
+						::SendMessage(hwnd, WM_SIZE, 0, 0);
+					}
+
 					return 0; // abort quitting
 				}