To create major graph object.
int Create( LPCSTR lpcszXFName, DWORD dwCntrl = 0, const TreeNode & trGUI = NULL, int nROIShape = SHAPE_RECT )
Returns 0 for no error.
-1, no active graph window in current project.
-2, no valid graph layer.
1, the major graph object not created successfully.
2, when fail to set trGUI.
3 and 4, when fail to create the attached graph object.