TGListBox inside TGCanvas container not shrinks down

canvasResize.c

#include <TGClient.h>
#include <TGCanvas.h>
#include <TGListBox.h>
#include <TGFrame.h>

class MyMainFrame : public TGMainFrame {
public:
   MyMainFrame(const TGWindow *p, UInt_t w, UInt_t h);
   virtual ~MyMainFrame();

   ClassDef(MyMainFrame, 0)
};

MyMainFrame::MyMainFrame(const TGWindow *p, UInt_t w, UInt_t h) : TGMainFrame(p, w, h) {
   // Create canvas with white background
   TGCanvas* canvas = new TGCanvas(this);
   TGCompositeFrame* container = new TGCompositeFrame(canvas->GetViewPort(), 10, 10, kOwnBackground);
   container->SetBackgroundColor(TColor::Number2Pixel(kGray+1));
   canvas->SetContainer(container);
   AddFrame(canvas, new TGLayoutHints(kLHintsLeft | kLHintsTop | kLHintsExpandX | kLHintsExpandY, 10, 10, 10, 10));

   // Add child ListBox (breaks layout - scrollbars appear when decreasing window size)
   TGListBox* listBox = new TGListBox(container);
   container->AddFrame(listBox, new TGLayoutHints(kLHintsNormal | kLHintsExpandX | kLHintsExpandY, 20, 20, 20, 20));

   SetWindowName("TGCanvas issue");
   SetWMSizeHints(300, 300, 1000, 1000, 1, 1);
   MapSubwindows();
   Resize(GetDefaultSize());
   MapWindow();
}

MyMainFrame::~MyMainFrame(){
   Cleanup();
}

void canvasResize(){
   new MyMainFrame(gClient->GetRoot(), 300, 300);
}