Reputation: 2033
I've been having problems with the ComboBox control. I'm no expert in GUI, but I know this problem is related to the control's focus.
For some reason, the ComboBox does not lose its focus when I click outside of it. Say for example:
OR
Note that the ComboBox only has the DropDownStyle set to ComboBoxStyle.DropDownList. This means that it's the default ComboBox behavior. I thought that the default behavior was that the ComboBox would lose its focus when you clicked out of it, or on another control (button or ComboBox). It is not the case here, why?
UPDATE: What I need is some sort of ActiveComponent = null. The behavior should be similar to the one of Visual Studio were you select Debug or Release (ComboBox) in the standard toolbar. Currently, if I click outside of the ComboBox, it is still focused.
Upvotes: 7
Views: 29570
Reputation: 442
The way I did it as follow.
Step 1 - Create a method that returns all given controls on the form
public IEnumerable<Control> GetAllControls(Control control, Type type)
{
var controls = control.Controls.Cast<Control>();
return controls.SelectMany(ctrl => GetAllControls(ctrl, type))
.Concat(controls)
.Where(c => c.GetType() == type);
}
Step 2 - Create a custom event
private void ChangeComboFocus(object sender, EventArgs e)
{
SendKeys.Send("{TAB}");
}
Step 3 - Bind the event finally on form load
private void ClientRegistrationForm_Load(object sender, EventArgs e)
{
var comboxes=_Helper.GetAllControls(this, typeof(ComboBox)).ToList();
if (comboxes != null)
{
foreach (ComboBox item in comboxes)
{
item.SelectedIndexChanged +=new EventHandler(this.ChangeComboFocus) ;
}
}
}
Upvotes: 0
Reputation: 449
private void drp_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == 13)
{
SendKeys.Send("{TAB}");
}
}
or use
this code on control leave function :
private void drp_Leave(object sender, KeyPressEventArgs e)
{
SendKeys.Send("{TAB}");
}
Upvotes: 0
Reputation: 4641
After SendKeys.Send("{ESC}")
; ComboBox
still regains focus;
Setting CausesValidation
to false on the combo box didn't help me as well.
Here is how I resolved this problem:
Suppose you have another control, for example System.Windows.Forms.PictureBox pbxChart
, and user wants to move focus right there, after changing values in combobox (selecting by Left Click or MouseWheel)
.
So I added :
private void pbxChart_Click(object sender, EventArgs e)
{
pbxChart.Focus();
}
in MouseClick EventHandler
, which resolved the problem.
Upvotes: 1
Reputation: 56
I know this has been a while for this post, but maybe it would help someone in the future who comes across the same problem. I struggled for few days with this, but finally figures it out.
if you set CauseViolation to false, then you are not solving the problem and databinding stops working.
When you mind SelectedItem to the property like so
combobox.DataBindings.Add("SelectedItem", someObject, "MySelectedItemProperty", false, DataSourceUpdateMode.OnPropertyChanged)
combobox calls the Equals method of the object that you use in the list which assigned to your DataSource. In my case, I needed to overwrite Equals method in this object. For whatever stupid reason, combobox calls this method and passes System.DBNull before actually passing the right object type for comparison. This is where violation occurred in my case and causing violation to fail, hence not releasing the cursor from the combobox. Also the weird part was that the program did not stop when Exception was caused in my Equals method.
Once I added this code
if (obj.GetType() != this.GetType())
return false;
to my Equals method, everything worked fine. Hope it helps someone.
Upvotes: 0
Reputation: 1
The dictionary that combobox take the values has, type index, type value, the type index have to be the same type in your class properity bindingded on combobox. If the types was diferent the combobox never will lose focus.
Upvotes: 0
Reputation: 19
In ***form.Designer.vb
you have some code for each combobox like:
'OrgDetailsIDComboBox
'
Me.OrgDetailsIDComboBox.DataBindings.Add(New System.Windows.Forms.Binding("Text", Me.MedicoLegalBindingSource, "OrgDetailsID", True))
Me.OrgDetailsIDComboBox.DataBindings.Add(New System.Windows.Forms.Binding("SelectedValue", Me.MedicoLegalBindingSource, "OrgDetailsID", True))
Me.OrgDetailsIDComboBox.DataSource = Me.OrgBindingSource
Me.OrgDetailsIDComboBox.DisplayMember = "Place"
I fixed the problem by commenting out the first line of code (includes string Forms.Binding("Text", )
. So it seems only the statement for SelectedValue
is required.
Upvotes: 0
Reputation: 47
All you have to do is:
The property is intended for some other purpose but it works for this scenario too.
Upvotes: 3
Reputation: 5286
I experienced a similar problem, but the control was recursively losing and regaining focus; the LostFocus
event handler was being called, but the control immediately regained focus. Setting the CausesValidation
property to false
had no effect.
In my case, I had bound to the SelectedValue
property instead of the Text
property when binding to a custom object. Because I manually specified the ComboBox item collection and did not provide a data source, the ValueMember
property was missing or invalid (so of course the SelectedValue
property was no use.)
Changing my binding to use the Text
property solved the issue.
Upvotes: 2
Reputation: 21
Try Leave event instead of LostFocus.
Try Enter event instead of GotFocus.
Upvotes: 1
Reputation:
I had the similar problem and tried all the method you guys suggested. Unfortunately, none of them works. Here is my "simple" solution: send a "ESC" key stoke after you change the SelectedIndex.
ComboBox1_SelectedIndexChanged(object sender, System.EventArgs e)
{
# do whatever you were doing
...
...
SendKeys.Send("{ESC}");
}
It worked for me.
Upvotes: 2
Reputation: 1279
You may want to take a look at This topic. Try setting CausesValidation to false on the combo box, see if you can leave it. If an exception is thrown in the OnValidating event handler, it won't deselect the box.
Upvotes: 19
Reputation: 2257
Are you sure the problem isn't because neither your frame or your other combobox have a way to gain focus?
Upvotes: 3
Reputation: 97811
So what exactly are you saying? Are you saying that your _LostFocus() event handler is not being called? If so, the first place I would look is in your designer-generated event handler mapping code. Sometimes that has a way of being disassociated by doing certain things in the designer (it's rare these days, though...)
Upvotes: 2