View source for WM BUTTON1MOTIONSTART

This message occurs when the operator initiates a drag operation by moving the mouse while pressing button one on the pointing device.

==Syntax==
<pre>
param1
    POINTS ptspointerpos; /* Pointer position. */

param2
    USHORT fsHitTestres; /* Hit-test result. */
</pre>

==Parameters==
;''ptspointerpos'' (POINTS) - input: Pointer position in window coordinates relative to the bottom-left corner of the hit-tested window, when the drag operation is started.
;''fsHitTestres'' (USHORT) - input: Hit-test result. Provides the hit-test result, which determines the window to be associated with this message. For details of the possible values, see [[WM_HITTEST]].

==Returns==
;''rc'' (BOOL) - returns: Processed indicator.
:TRUE: Message processed
:FALSE: Message ignored

==Remarks==
This message is posted to the application queue associated with the window that is to receive the pointer-button information.

==Default Processing==
The default window procedure sends the message to the owner window if it exists, otherwise it takes no action on this message, other than to set ''rc'' to FALSE.

[[Category:Messages]]