bug#3468: drag and drop text

[Cecilio Pardo <cpardo@imayhem.com>]

On 05/10/2024 13:07, Eli Zaretskii wrote:

>> There is no malloc/strdup.
> 
> Well, there are still 2 calls to malloc in w32_createwindow.  Any
> reasons not to call xmalloc instead?  Can w32_createwindow be called
> before we call init_heap?

[...]

> Do we ever have to free the two memory chunks we allocate here?  Like
> when the window is disposed of?

They are freed in w32_drop_target_Release, which is called internally 
when we call RevokeDragDrop while handling the WW_EMACS_DESTROYWINDOW on 
w32_wnd_proc.

As this runs on the input thread, I used malloc/free instead of 
xmalloc/xfree.  I could send a message to handle on w32_read_socket and 
then use xmalloc.

> This function should call block_input at entry and unblock_input
> before it exits, because we must make sure all the GlobalLock calls
> are paired with GlobalUnlock and GlobalFree, while functions we call
> here, process_dropfiles etc., all cons Lisp object, and therefore
> could potentially QUIT, which throws to top-level.

The function (w32_process_dnd_data) is called from within the 
block_input/unblock_input on w32_read_socket.

Should I add its own calls for clarity? Maybe just a comment?

Thanks.