> However, the kind of Drag&Drop you are asking about and need to use is the
> one that is controlled by the OS.  As such, you must implement it yourself
> manually.  Look in the Win32 API reference (win32.hlp or
> http://msdn.microsoft.com/search) at the RegisterDragDrop() and
> RevokeDragDrop() functions, and implementing the IDropTarget interface.

> Gambit

> "Florian Pose" <flor...@maculaweb.de> wrote in message
> news:3a341543$1_1@dnews...

> > I'm trying to drag files from the desktop in one of my listviews. It is
no
> > problem when I perform a Drag&Drop operation from one listview to
another
> > but from the desktop ? Why doesn't it work ?

> class MyDropTarget : public IDropTarget
> {
> public:
>     HRESULT DragEnter(IDataObject*, DWORD, POINTL, DWORD*);
>     HRESULT DragOver(DWORD, POINTL, DWORD*);
>     HRESULT DragLeave(void);
>     HRESULT Drop(IDataObject*, DWORD, POINTL, DWORD*);
>  };

> HRESULT MyDropTarget::DragEnter(IDataObject *pDataObject, DWORD
grfKeyState,
> POINTL pt, DWORD *pdwEffect)
> {
>     // your code
> }

> HRESULT MyDropTarget::DragOver(DWORD grfKeyState, POINTL pt, DWORD
> *pdwEffect)
> {
>     // your code
> }

> HRESULT MyDropTarget::DragLeave(void)
> {
>     // your code
> }

> HRESULT MyDropTarget::Drop(IDataObject *pDataObject, DWORD grfKeyState,
> POINTL pt, DWORD *pdwEffect)
> {
>     // your code
> }

> MyDropTarget *MDT;
> [...]
> RegisterDragDrop(ListView1->Handle, MDT);

> Gambit

> Florian Pose <flor...@maculaweb.de> wrote in message
> news:3a34a912$1_1@dnews...
> > Now I know, that I have to register my ListView as an OLE drop target.
But
> I
> > found no proper Informaition how to implement the IDropTarget neither in
> the
> > API help nor in MSDN ... :-(
> > Moreover the call of the function RegisterDragDrop returns an unknown
> > value...

> Is there something I forgot to declare in the derives class ?

> The only other thing I can think of is to also add the following functions
> to your TDropTarget-derived class as well, and see if they help at all:

> class MyDropTarget : public IDropTarget
> {
> private:
>     DWORD cRefs;
> public:
>     CContextMenuHandler();

>     // the following three functions come from the IUnknown interface
>     // which IDropTarget is derived from

>     STDMETHODIMP QueryInterface(REFIID riid, LPVOID *ppvObj);
>     STDMETHODIMP_(DWORD) AddRef(void);
>     STDMETHODIMP_(DWORD) Release(void);
> };

> CContextMenuHandler::CContextMenuHandler()
> {
>     cRefs = 0;
> }

> STDMETHODIMP MyDropTarget::QueryInterface(REFIID riid, LPVOID *ppv)
> {
>     *ppv = NULL;

>     if(IsEqualIID(riid, IID_IUnknown))
>         *ppv = this;
>     else if(IsEqualIID(riid, IID_IDropTarget))
>         *ppv = (IDropTarget*)this;

>     if (*ppv == NULL)
>         return E_NOINTERFACE;

>     ((LPUNKNOWN)*ppv)->AddRef();
>     return NOERROR;
> }

> STDMETHODIMP_(DWORD) MyDropTarget::AddRef(void)
> {
>     return ++cRefs;
> }

> STDMETHODIMP_(DWORD) MyDropTarget::Release(void)
> {
>     if (--cRefs != 0)
>         return cRefs;

>     delete this;
>     return 0;
> }

> Gambit

> "Florian Pose" <flor...@maculaweb.de> wrote in message
> news:3a360ca2$1_2@dnews...
> > Sorry, that I'm asking once more:
> > I declared the 4 Functions of the IDropTarget...
> > What can it be, if my RegisterDragDrop call produces an unknown error ?

> > Is there something I forgot to declare in the derives class ?