WinForms Focus, hotkeys and ‘saving data’

April 21, 2005 @ 11:57 pm

I'm a huge fan of utilizing Alt-S/Ctrl-S to save and move on in my applications. Saving tends to be the most common operation and that two finger salute is so universal it comes natural <g>...

But there's is one problem that I just cannot stand and it happens in just about every environment.

Problem: You’re in edit mode on a form, and you now are ready to exit so you hot-key Ctrl-S or Alt-S to save and… you end up loosing the changes in the last text/editbox you were editing. Basically Windows doesn’t recognize your hotkey action as a ‘moving off’ the control so the control’s internal value property (.Text in .NET) is not updated. So your code probably saves happily away not realizing that the value actually isn’t saved.

This is often insidious because you see all the rest of the data saved, just that one value isn't.

The workaround is easy enough but ugly. I usually have a method on the form that does something like this:

private void FixExitFocus()

{

if (this.ActiveControl != null)

{

// *** Force focus to 'save'

Control ctrl = this.ActiveControl;

this.lblSitename.Focus();

Application.DoEvents();

ctrl.Focus();

}

I then call this method, for anything that relies on the values on the form to perform an action. Usually that's a save, but also something that requires the live data from the form right now before it's even saved. This code basically shifts focus away and then back to the control which forces writing the data to the .Text property and the underlying databinding mechanism. In FoxPro you used to be able to cheat this by setting focus to the same control which would also work, which makes the job a lot easier, since you don’t have to go looking out for another control to focus on.

Maybe I’m not thinking about this right but short of walking the control collection and finding some control to set focus to then off I don’t see a generic solution here…

You also see this behavior in some major applications - I guess I automatically am in the habit of tabbing off everything before saving or explictly clicking on a button.

My current scenario specifically is a WinForm with Sandbar on it and using menu items that are hotkeyed. But the same behavior applies to the stock Toolbars and even button hotkeys.

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re: WinForms Focus, hotkeys and ‘saving data’
by Kevin Wright April 22, 2005 @ 1:12 am

What is the this.lblSitename that your code refers to?

Kevin

re: WinForms Focus, hotkeys and ‘saving data’
by Rich Hassler April 22, 2005 @ 9:11 am

How about adding a dummy control, setting focus to it, then deleting it after the save?

re: WinForms Focus, hotkeys and ‘saving data’
by Rick Strahl April 22, 2005 @ 2:20 pm

Kevin, lblSitename is just another label on the form. I guess the it could be generic is to simply run through the control collection, find the first visible control and set focus to it then back...

re: WinForms Focus, hotkeys and ‘saving data’
by Kevin Wright April 24, 2005 @ 2:43 am

> I guess the it could be generic is to simply run through the control collection, find the first visible control and set focus to it then back..

Any chance of a quick code snippet for those of us not very familiar with C#?

Would Rich's suggestion about adding a dummy control be either any quicker or easier to code generically?

Kevin

re: WinForms Focus, hotkeys and ‘saving data’
by Hector Correa April 24, 2005 @ 6:42 pm

I thought I should point out that this behavior also happens for controls inside of grids. To handle that I use: grdMyGrid.CurrentRow.EndEdit()

Of course you need to validate that CurrentRow is not null, and that you are editting a new row (grdMyGrid.CurrentRow.IsEdit/IsNew)

re: WinForms Focus, hotkeys and ‘saving data’
by Rick Strahl August 16, 2005 @ 11:06 pm

Here's the generic version you can stick on your Form subclass:

public void FixFocus()
{
if (this.ActiveControl != null)
{
// *** Force focus to 'save'
Control ctrl = this.ActiveControl;

if (this.Controls.Count > 0)
{
if (ctrl != this.Controls[0])
this.Controls[0].Focus();
else if (Controls.Count > 1)
this.Controls[1].Focus();

Application.DoEvents();
ctrl.Focus();
}

}
}

re: WinForms Focus, hotkeys and ‘saving data’
by Mr. Grammar January 31, 2006 @ 5:06 pm

"losing" not "loosing"

re: WinForms Focus, hotkeys and ‘saving data’
by Rick Strahl January 31, 2006 @ 9:28 pm

<g>... yes I know. Sloppy typing in the blog is not uncommon. I promise I'll do better, Pa!

re: WinForms Focus, hotkeys and ‘saving data’
by Mr. Grammar February 06, 2006 @ 10:48 am

No problem. Just don't start saying "Amount of objects".

This is a real b**** of a problem. It seems like we are left with nothing but hacky workarounds. I'll throw mine into the ring.

This assumes you have a label control somewhere on the form. It finds the first one, so you can optimize by making sure a label gets added first (go to designer-genrated code and make sure first control added to form's controls collection is label1 or whatever). I did this just to minimize potential problems if you go setting focus to other controls with events. You could add a trace statement in case no label is found, blah blah blah. Notice I'm using MDI. I call this in my controller from several places, like New(), Open(), etc. Now I don't worry about placing a special control or subclassing my form, aren't I brilliant? Don't answer.

private void ForceUpdateOfFocusedControl()
{
// This is to get around a databinding problem in Winforms: a control
// doesn't update its datasource unless the user sets the focus to
// another control on the same form. BindingManagerBase.PullData()
// is protected, so we're left with this cheesy workaround.
Form form = mainWindow.ActiveMdiChild;
if (form != null)
{
Control active = form.ActiveControl;
if (active != null && active.DataBindings.Count > 0)
{
foreach (Control other in form.Controls)
{
if (other is Label)
{
other.Focus();
active.Focus();
return;
}
}
}
}
}

re: WinForms Focus, hotkeys and ‘saving data’
by Mr. Grammar February 06, 2006 @ 10:50 am

Why do websites love to eat spaces when parsing code? I created a work of art. I shall loose a plague on you.

re: WinForms Focus, hotkeys and ‘saving data’
by Kenneth June 22, 2006 @ 3:58 pm

Had a similar problem. I think the idea is to call the Validate method off the form.

Like:
this.Validate();
Or:
Form1.Validate();

From MSDN about the Form Validate method:
Overloaded. Verifies the value of the control losing focus by causing the Validating and Validated events to occur, in that order. (Inherited from ContainerControl.)

re: WinForms Focus, hotkeys and ‘saving data’
by Dan Doyon August 04, 2006 @ 10:45 am

this.Validate() was the needful, thanks Kenneth.