Subclassing and Hooking with Visual Basic

Creating the Subclassing Application

The application we will create in this section subclasses the Save As common dialog box. This application has one form module called frmMain.frm, which is displayed in Figure 5-7. The nondefault properties of this form are listed in Table 5-5. The form contains a command button control called Command1 and a text box control called Edit1.

Figure 5-7. The main form of the sample application

Table 5-5. Nondefault Properties of frmMain and Its Controls

Control Name	Property Name	Property Value
frmMain	Caption	Ch5 - Common Dialog Subclassing Example
frmMain	BorderStyle	3-Fixed Dialog
frmMain	Top	0
frmMain	Left	0
frmMain	Height	3420
frmMain	Width	5760
Command1	Caption	Display Subclassed Dialog
Command1	Top	60
Command1	Left	60
Command1	Height	852
Command1	Width	1212
txtMsg	Multiline	True
txtMsg	Top	60
txtMsg	Left	1380
txtMsg	Height	2952
txtMsg	Width	4272

Clicking the button control creates a Save As common dialog box, subclasses it, and displays it. The Save As dialog is modified to include the extra controls that are contained in our resource DLL. This dialog is displayed in Figure 5-8.

Figure 5-8. The subclassed Save As common dialog box

The first thing you might notice about this new dialog is that ...