Combobox default problem

[chris in grimsby]

I have a combobox of dropdownlist style as one of the controls on a
tabbed form.

The list is populated by setting the DataSource property to a dataset
and then the DisplayMember and ValueMember properties are set to the
names of 2 of the fields in the dataset.

I noticed that when the form displays, the combobox defaults to the
first item in the list, not to blank (selectedindex=-1) as I would
have expected. I can use the Form_Activated event to set the
selectedindex=-1 and that is ok, until a different tab is selected
followed by this tab. Now the selectedindex=0 again and the combobox
shows the first item in the list again, even though the index change
event didnt fire.

 

[Herfried K. Wagner [MVP]]

* (e-mail address removed) (chris in grimsby) scripsit:

The list is populated by setting the DataSource property to a dataset
and then the DisplayMember and ValueMember properties are set to the
names of 2 of the fields in the dataset.

I noticed that when the form displays, the combobox defaults to the
first item in the list, not to blank (selectedindex=-1) as I would
have expected. I can use the Form_Activated event to set the
selectedindex=-1 and that is ok, until a different tab is selected
followed by this tab. Now the selectedindex=0 again and the combobox
shows the first item in the list again, even though the index change
event didnt fire.

BUG: ComboBox Does Not Clear When You Set SelectedIndex to -1
<URL:http://support.microsoft.com/?id=327244>

 

[Edward Forgacs]

I have also experienced this issue with MDI child forms. The fix is the same
as for tab controls:
give the combobox a different binding context to the form (which is the
default). e.g.

comboBox1.BindingContext = New BindingContext()