Combo Like User Control

  • Thread starter Thread starter Jeff Gaines
  • Start date Start date
J

Jeff Gaines

I am putting together a control which will work like a combo box - except
its drop down will be a Tree View.

When I use the control in a panel on a form I can't resize it to allow for
the drop down part - it is constrained by the size of its parent panel -
yet a combo Box can open up and without any such constraints.

Is there a trick to allowing a control to open up (temporarily) over other
controls? I seem to remember from a while back that this could be achieved
by placing the control on a borderless form, but it seems a lot of work
when all I need is Combo like behaviour.
 
Controls are child windows they are clipped by the size of theur parent.
Popup windows are not on the other hand. AFAIK using forms is probably the
only way you can pull this off with WindowsForms.
 
Controls are child windows they are clipped by the size of theur parent.
Popup windows are not on the other hand. AFAIK using forms is probably the
only way you can pull this off with WindowsForms.
Click to expand...

Thank you, Stoitcho - at least I understand why now :-)
 
Hi Jeff,

The drop down part of a ComboBox control is a separate window, which
enables the drop down part to open up over other controls.

To implement a custom drop down window, we could use a WinForm, whose
FormBorderStyle property is set to None. But this solution is not very
good, because the form would take the focus and inactivate the main window
form. The functionality of the dropdown would be difficult to manage too.

A better solution is to derive a class from NativeWindow and create a popup
window, similar to a tooltip window, that can be shown using the
SW_SHOWNOACTIVATE setting and ShowWindow function via interoop. A class
created in this way would mimic the behaviour of the base Win32 controls
and it would be easier to create the desired internal functionality such as
item selection and so-on.

You may visit the following link for more information on how to do it using
NativeWindow.

http://vbaccelerator.com/home/NET/Code/Controls/Popup_Windows/Popup_Windows/
article.asp

I searched the web site ' www.codeproject.com' and also found a smarter
solution of using ToolStripDropDown to implement the drop down window. You
may visit the following link for more information on how to do this.

http://www.codeproject.com/useritems/simplepopup.asp

Hope this helps.
If you have any question, please feel free to let me know.


Sincerely,
Linda Liu
Microsoft Online Community Support

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Hi Jeff,

The drop down part of a ComboBox control is a separate window, which
enables the drop down part to open up over other controls.
Click to expand...

[snipped]

Many thanks, Linda - they are very useful examples :-)
 
Hi Jeff,

Thank you for your prompt response.

How about the your implementing the custom drop down window? If you need
our further assistance, please feel free to let me know.

Thank you for using our MSDN Managed Newsgroup Support Service!


Sincerely,
Linda Liu
Microsoft Online Community Support
 
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