The main question has already been answered, but...

It is good that you called "free", but this is an unnecessary heap allocation that could lead to a memory fragmentation leak if you forget. Don't use the heap for stuff like this:

		int m_Width, m_Height;
		LPRECT rect = (LPRECT)malloc(sizeof(RECT)); // <- Why are you doing this?
		if (GetWindowRect(m_Hwnd, rect))
		{
			m_Width = rect->right - rect->left;
			m_Height = rect->bottom - rect->top;
		}
		else return; // Guaranteed memory leak if the function returns here. Where is the call to free?

		free(rect); // <- ??

Also, why are you using malloc/free instead of new/delete?

In this case, the RECT is allocated on the stack and is automatically deallocated when the function goes out of scope:

		int m_Width, m_Height;
		RECT rect;
		if (GetWindowRect(m_Hwnd,&rect))
		{
			m_Width = rect.right - rect.left;
			m_Height = rect.bottom - rect.top;
		}
		else return;

I use vs2013. compiling dll c++\cli and when i using LPRECT rect without malloc() this value becomes 0x00000000 and GetWindowRect() return false.

I am sorry, my english is bad

RECT rect;
if (GetWindowRect(m_Hwnd, &rect))
{
	m_Width = rect.right - rect.left;
	m_Height = rect.bottom - rect.top;
}

// rect is now freed automatically
// you never leak memory, you never need to manually delete it.

Just don`t see, it`s work. Thanks alot for your help.

Just don`t see, it`s work.

I am sorry, my english is bad