Thread: superclassed treeview

i created a class that encapsulated a superclassed tree view control. however, i can only use the class once in my program. i have added a check so that it doesn't try to Register the class again, and the error occurs during CreateWindowEx. here is the class:

Code:

class cTree
{
private:
protected:
public:
	cTree(HWND parent=NULL);
	~cTree();
	static LRESULT CALLBACK cTreeProcA(HWND hwnd,UINT msg,WPARAM wParam,LPARAM lParam);
	virtual LRESULT CALLBACK cTreeProc(HWND hwnd,UINT msg,WPARAM wParam,LPARAM lParam);
	HWND Create(HWND parent,HINSTANCE hInstance);
	HTREEITEM Add(char *chText);
	HTREEITEM Add(char *chText,HTREEITEM parent);
	//HTREEITEM Add(char *chText,HTREEITEM parent,HTREEITEM insAfter);

	HWND hTree;
	HWND hParent;
	WNDPROC wpPrev;
	HINSTANCE hInst;
	HIMAGELIST hList;
	int left,top,width,height;

	static BOOL classReg;
};

HWND cTree::Create(HWND parent,HINSTANCE hInstance)
{
	WNDCLASSEX wcx;
	
	hInst=hInstance;
	hParent=parent;

	if (classReg!=1)
	{
		GetClassInfoEx(NULL,WC_TREEVIEW,&wcx);
	
		wpPrev=wcx.lpfnWndProc;
		wcx.lpfnWndProc=(WNDPROC)cTreeProcA;
		wcx.hInstance=hInst;
		wcx.lpszClassName="cTree";
		wcx.cbSize=sizeof(wcx);
		if (!RegisterClassEx(&wcx))
			return NULL;
	}
	classReg=1;

	hTree=CreateWindowEx(WS_EX_CLIENTEDGE,"cTree",NULL,
					WS_BORDER | WS_CHILD | WS_VISIBLE | 
					TVS_HASLINES | TVS_HASBUTTONS | TVS_LINESATROOT,
					left,top,width,height,hParent,NULL,hInst,(void *)this);
	if (!hTree)
		return NULL;

	return hTree;
}

the way that i implement the class is this:

Code:

hwnd=CreateWindowEx(//parent window);
ShowWindow(...);
UpdateWindow(...);

cTree *ct1=new cTree(hwnd);
//set dimensions
ct1->Create(hwnd,hInst);

cTree *ct2=new cTree(hwnd);
//set dimensions
ct2->Create(hwnd,hInst);

only the first tree view control is created. for any subsequent attempts, CreateWindowEx returns NULL. i cant remember ever using a superclass twice in a program, but surely it's possible.