Rework of SetCursor for Win32

[thennequin]

Preload cursor at creation to avoid loading of cursor when event WM_SETCURSOR is called.

::SetCursor(LoadCursor(NULL, IDC_ARROW));

To

m_pCusorArrow = LoadCursor(NULL, IDC_ARROW);
. . .
::SetCursor(m_pCursorArrow);