Hello friends!

I'm developing a custom control inherited from GroupBox class. As a inherited group box, I don't know why, but the visual representation of the control is not showed in design time. Instead I get a gray screen with a message "drag controls here...bla bla..." or something else. Until here it's ok, the problem is I have to add a datagridview inside the control and just dragging it from toolbox didn't solve. Trying to solve that, I instantiate the DGV at the custom control New method and I added the control via Me.Controls.Add. In order to access the DGV inside the control, I added a property returning it. All woked well, except the fact that If I click the Columns property (...) button of the datagridview at properties window, I get a error "object reference not set to an instance of an object".

It seems by adding a control via Controls.Add does not actually "create it" at design time.

How can I solve that?

Thank you
Regards,
Guilherme.

There is no usable designer for controls derived from a control class. You'll need to use a UserControl instead. Dock a GroupBox inside of it, then add whatever controls you need.

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Hans Passant.

Did you add a common class or a component ? If you're using a component, you will not get it from toolbox. You can try add a common class and inherit from GroupBox, then you willuse it.

I used a common class. Nobugz, I simply can't dock a visible GroupBox to my user control because with the component ready and working, I can't drag any other item inside the groupbox, I can't make any other control be a control of the GroupBox inside my Custom control. How can do it?

thanks for reply.

Not quite sure what you mean. If you need to add additional controls after putting your custom control on a form, you'll need a designer derived from ParentControlDesigner. Ask questions about that in the Windows Forms Designer forum. If you simply derive your own class from GroupBox, it will act like a GroupBox at design time without any additional work needed. But without the ability to add controls to it to make a composite control like UserControl.

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Hans Passant.