Subclassing and Hooking with Visual Basic

A Single-Thread Example

The example presented here is simple in structure: it watches for all mouse messages and displays each message in the text box. Figure 13-3 shows a screenshot of this application. To use this application, simply click the hook button contained in the MOUSE frame. This will install the WH_MOUSE hook and start displaying the mouse messages in the text box. The text box will fill up rather quickly as the mouse messages are fired, even though the mouse must be within the borders of the window for this hook to capture a mouse message. A system-wide mouse hook will catch all mouse messages for all windows that are visible on the screen, including the desktop; had we implemented it, output from this hook to the text box would have been completely overwhelming.

Figure 13-3. A screenshot of the single-threaded mouse hook application

Table 13-2 presents the nondefault properties of the form and its controls.

Table 13-2. Nondefault Properties of the Form and Its Controls

Object Type	Property Name	Property Value
Form	Name	Form2
Form	Caption	“WH_MOUSE Hook Demo”
Form	Top	420
Form	Left	132
Form	Height	3555
Form	Width	8655
Frame	Caption	“MOUSE”
Frame	Name	Frame1
Frame	Top	120
Frame	Left	120
Frame	Height	1335
Frame	Width	1155
TextBox	MultiLine	True
TextBox	Top	240
TextBox	Left	1380
TextBox	Height	3255
TextBox	Width	7215 ...