INFO: Remove Information About Unused ActiveX Controls

MORE INFORMATION

The Make tab under the Project Properties menu has the following option:

If this option is selected, any ActiveX controls that have been referenced but not sited within the project will not have their license information included in the final compiled executable.

Visual Basic allows ActiveX controls to be dynamically loaded at run-time. This feature raises concerns about being able to load/use controls which a program legally should not be able to use.

Visual Basic has two ways of using an ActiveX control legally:

• Include the ActiveX control license within the compiled executable.
• Load the license for an ActiveX control during run-time before loading the actual control.

Both ways ensure that the license for the control is checked (either during development or during run-time) prior to the control being used.

A license that is included in a compiled executable will be part of the Licenses collection object.

In order to add controls dynamically without concern about the License collection object, make sure that the "Remove information about unused ActiveX Controls" option is deselected.

Adding an ActiveX Control During Run-time That Requires a License

The following sample shows how to reference a control in Visual Basic and add it dynamically during run-time without having to use the Licenses collection object:

1. Create a new Standard EXE project in Visual Basic. Form1 is created by default.
2. Select Components from the Project menu and select "Microsoft Hierarchical FlexGrid Control 6.0 (OLEDB)."
3. Add a CommandButton (Command1) to Form1.
4. Add the following code to Form1:
   

         Option Explicit
   
         Private Sub Command1_Click()
   
            Dim ctlTest As VBControlExtender
   
            ' add a control dynamically to this form
            Set ctlTest = Form1.Controls.Add _
            ("MSHierarchicalFlexGridLib.MSHFlexgrid","ctlTestControl")
   
            ' position and show the form
            ctlTest.Move 100, (Command1.Top + Command1.Height) + 100
            ctlTest.Visible = True
   
         End Sub
   
         Private Sub Form_Load()
   
            ' move the command1 button to the corner for appearance.
            Command1.Move 100, 100
   
         End Sub
   
   						

5. Compile the Project (Project1.Exe).
6. Run the compiled Project.
7. Click the "Command1" button. The following error will appear:
   
   Run-time Error "731"
   
   "In order to use "MSHierarchicalFlexGridLib.MSHFlexgrid", you must specify a license string for the control. Use Licenses.Add to add the license string to the Licenses collection."
   Although "Microsoft Hierarchical Flexgrid Control 6.0 (OLEDB)" is referenced within the project, the License information for the controls were removed because none of the controls were sited on any forms. Running within the IDE would result in run-time error "50153."
8. In the design environment, select Project1 Properties from the Project menu, then the "Make" tab on the Project1 Properties dialog.
9. Make sure that the "remove information about unused ActiveX controls" option is not selected.
10. Make the project again.
11. Run the compiled project.
12. Click the "Command1" button. This time the Hierarchical Flexgrid Control will be instantiated and will be sited on the form.