Fix saving/restoring window position for maximized windows

Save both the normal window geometry and its maximized position instead
of saving just its current position. This fixes restoring geometry of
the maximized windows as previously they were always restored on the
primary monitor, as their original position was lost.

Use the native {Get,Set}WindowPlacement() functions for a MSW-specific
wxTLWGeometry implementation to achieve this.

Closes #16335.

tests/persistence/tlw.cpp

@@ -101,6 +101,59 @@ TEST_CASE_METHOD(PersistenceTests, "wxPersistTLW", "[persist][tlw]")
         CHECK(!frame->IsMaximized());
         CHECK(!frame->IsIconized());
 
+        // Next try that restoring a minimized frame works correctly: for
+        // Iconize() to have effect, we must show the frame first.
+        frame->Iconize();
+        frame->Show();
+
         delete frame;
     }
+
+    // Check geometry after restoring the minimized frame.
+    {
+        wxFrame* const frame = CreatePersistenceTestFrame();
+
+        CHECK(wxPersistenceManager::Get().RegisterAndRestore(frame));
+
+        CHECK(!frame->IsMaximized());
+        CHECK(frame->IsIconized());
+
+        frame->Restore();
+
+        CHECK(pos.x == frame->GetPosition().x);
+        CHECK(pos.y == frame->GetPosition().y);
+        CHECK(size.x == frame->GetSize().GetWidth());
+        CHECK(size.y == frame->GetSize().GetHeight());
+
+        // Next try that restoring a maximized frame works correctly: again,
+        // for it to be really maximized, it must be shown.
+        frame->Maximize();
+        frame->Show();
+
+        delete frame;
+    }
+
+    // Check geometry after restoring the maximized frame.
+    //
+    // This test currently fails under non-MSW platforms as they only save the
+    // maximized frame size, and its normal size is lost and can't be restored.
+#ifdef __WXMSW__
+    {
+        wxFrame* const frame = CreatePersistenceTestFrame();
+
+        CHECK(wxPersistenceManager::Get().RegisterAndRestore(frame));
+
+        CHECK(frame->IsMaximized());
+        CHECK(!frame->IsIconized());
+
+        frame->Restore();
+
+        CHECK(pos.x == frame->GetPosition().x);
+        CHECK(pos.y == frame->GetPosition().y);
+        CHECK(size.x == frame->GetSize().GetWidth());
+        CHECK(size.y == frame->GetSize().GetHeight());
+
+        delete frame;
+    }
+#endif // __WXMSW__
 }