If the mouse up finishes the drag (see the below Remarks for more information on why a mouse up might not finish a drag operation) ReleaseCapture() must be called to allow other windows access to mouse messages.Ī drag operation can usually be aborted by pressing ESC. Note that various drag enabled controls detect when a drag begins and send their parent a message such as LVN_BEGINDRAG. Once the beginning of a drag operation is confirmed, call SetCapture(). If the user is clicking on something draggable, use the DragDetect() API to detect if a drag operation is beginning. To implement a drag operation in your application, you would implement the following message handlers: WM_LBUTTONDOWN WM_RBUTTONDOWNĪ drag operation generally starts when the user clicks on something, and begins to move the mouse. Implementing a Drag operation using SetCapture All windows on all threads if those windows and the window with capture share the same top-level window.Once the capture has reverted to background capture, the window only receives mouse messages for: Here are the differences between foreground and background capture: Foreground CaptureĪ window with foreground capture receives all mouse messages for all windows in the system. If, at any time, all the mouse buttons are released, the mouse capture will automatically revert to the background. Otherwise (if the current thread is not the foreground thread, or no mouse buttons are held down), the window merely gets background capture. At least one mouse button is being held down.The current thread is the foreground thread (i.e., it owns the foreground window).Foreground capture is obtained when the following two conditions are met: In addition, there are two types of capture, that I call foreground and background capture. A window can request mouse capture by calling the SetCapture() API, and that window has the mouse capture until either the ReleaseCapture() API or SetCapture() is called directing the mouse capture to a different window. Only one window can have the mouse capture at a time. You can understand how best to use SetCapture() in your application if you understand the following limitations of using mouse capture: The action of the SetCapture() API is somewhat complex, and not well documented in the Platform SDK. You want to know what window the mouse is over.You are implementing some sort of drag and drop interface.You need a reliable mouse over detection.The implementation of the UI of an application sometimes requires the capture of the mouse.

Dragdetect windowmanager