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Try overriding the combobox control. Very, very basic example below;
class ComboBoxWidget: System.Windows.Forms.ComboBox
{
#region private member variables
private int _selectedIndex = -1;
#endregion
#region overrides
protected override void OnSelectedIndexChanged( EventArgs e )
{
if( this.SelectedIndex != this._selectedIndex )
{
this._selectedIndex = this.SelectedIndex;
base.OnSelectedIndexChanged( e );
}
}
public override int SelectedIndex
{
get
{
return base.SelectedIndex;
}
set
{
this._selectedIndex = value;
base.SelectedIndex = this._selectedIndex;
}
}
#endregion
}
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How to call .mht files in C# project?
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What is an mht file ?
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
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In Visual Studio Team System, the manual test case is saved as .mht file. Manual tests are nothing more than a .mht file that has been added to your project, when you create a Manual Test.
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using System.Diagnostics
Process.Start("notepad","D:\\somefile.txt");
this works, though there is probably a better way to do it
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I have a simple C# application with an embedded Internet Explorer Active X component for quickly displaying and printing HTML pages. This application is not seen by PC Anywhere. If this application is active on the screen it will show the background of the host and part of the screen will be inaccessable by the remote computer. Has anyone else seen this or better have a fix for it?
Thanks,
Darrell
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Any form that has any sort of transparency, is not visible over a remote connection. Is that the problem ?
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
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Remote desktop doesn't support directx
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I need some help with being able to open a document that is listed in a datatable and is displayed in a datagridview. The code below returns a series of results from a database and these results include the file paths of files on my computer. What I want to be able to do is doulble click on a particular file path in the link column and have that file open.
Hits hits = searcher.Search(query);
DataTable dt = new DataTable();
dt.Columns.Add("link", typeof(string));
for (int j = 0; j < hits.Length(); j++)
{
Document doc = hits.Doc(j);
DataRow row = dt.NewRow();
row["link"] = doc.Get("link");
dt.Rows.Add(row);
}
MessageBox.Show("Search Complete", "", MessageBoxButtons.OK);
return dt;
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I have solved the problem, just in case anyone is interested.
private void dgv_CellContentDoubleClick(object sender, DataGridViewCellEventArgs e)
{
SearchIndex search = new SearchIndex();
search.docOpen(this.dgv.CurrentCell.Value.ToString());
}
public void docOpen(string path)
{
Process proc = new Process();
proc.StartInfo.FileName = "iexplore";
proc.StartInfo.Arguments = path;
proc.Start();
}
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This problem has to do with updating a control/dataset based on the DataRecevied event of the serial port. Now I know you are thinking cross threading (which it might be) but let me explain.
I have a dataset in the main UI form that is databound to a number of controls. When I change the values of the dataset the bound controls update. This is fine, but when I update the values of the dataset via the DataReceived event the values DON'T update? To illlustrate the problem simply I have stripped down the code to it's most basic form. I hope someone can shed some light on the problem.
<br />
public Form1()<br />
{<br />
InitializeComponent();<br />
}<br />
<br />
private void Form1_Load(object sender, EventArgs e)<br />
{<br />
UnitDataSet uds = new UnitDataSet();<br />
uds.DIns.ReadXml("Data.xml");<br />
<br />
_comms = new Comms(uds);<br />
<br />
Label lblInputState = new Label();<br />
panel1.Controls.Add(lblInputState);<br />
<br />
lblInputState.DataBindings.Add("Text", uds.Tables["DIns"], "state");<br />
}<br />
<br />
public void button1_Click(object sender, EventArgs e)<br />
{<br />
_comms.ChangeValue();<br />
}<br />
}<br />
<br />
============================================================<br />
<br />
class Comms<br />
{<br />
SerialPort _sp;<br />
UnitDataSet _uds;<br />
<br />
public Comms(UnitDataSet uds)<br />
{<br />
_uds = uds;<br />
_sp = new SerialPort("COM7", 9600, Parity.None, 8, StopBits.One);<br />
_sp.DataReceived += new SerialDataReceivedEventHandler(_sp_DataReceived);<br />
_sp.Open();<br />
}<br />
<br />
private void _sp_DataReceived(object sender, SerialDataReceivedEventArgs e)<br />
{<br />
ChangeValue();<br />
}<br />
<br />
public void ChangeValue()<br />
{<br />
bool tmp = (bool)_uds.Tables["DIns"].Rows[0]["state"];<br />
_uds.Tables["DIns"].Rows[0]["state"] = !tmp;<br />
}<br />
}<br />
Visual C# Express 2005
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If you enable the debugger to break on all CLR exceptions (Tools -> Exceptions -> Check the box) and run the form under debug mode if it's a one of the many cross-thread problems then the debugger should trap the exception.
Try using in the DataReceived handler, this.Invoke(ChangeValue), which will be thread-safe.
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Thanks for you comments Ed. I can't seem to find Tools -> Exceptions. I'm using Visual C# express? I'll try your invoke method now.
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there is no this.invoke() ??!
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The Invoke method is a member of the Form data type, it's used to provide thread-safe updates of the form's controls / components. If you're not using a form you might want to take a look at my article[^] :->, which will allow you to do the thread-safe invocation from anywhere.
The Exceptions box is under Debug | Exceptions sorry, I don't know about the express edition but that's where it is in the Standard edition of VS.
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Thanks Ed! Actually I saw you article today when I was searching for help. You are right it's not a form. I scanned over your article but it seemed quite complex to me (I still haven't really got my head around delegates or generics) but I'm fast running out of options so I'm going to study it and hopefully I'll find the answer.
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The article actually needs an update, which will make it simpler to use (removes generics). I've got the changed code here[^]. Basically from inside your DataReceived handler all you need to do is call:
InvocationHelper.Invoke(this.ChangeValue); All the delegate is is a pointer to a function (if you know C), if you don't it's basically a variable which stores information about a particular function or method, you can then pass this variable around as a normal variable, and you can also invoke the function the delegate points to as well.
The helper routine basically just bubbles up through the class hiearchy to see if the class implements the interface ISynchronizewhatever, this just defines the Invoke method and means that the class can do things in a thread-safe manner.
PS, generics are quite simple to understand and incredibly useful once you know how.
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Thanks again Ed! I've just arrived and work this morning and it's great to see your message. Well, although I'm new to generics, I am actually using them in my project already. I'm sure I'll use them more and more as they do seem well suited to many situations, I'm just getting to the 'once you know how part'. The word delegate makes me nervous, but I'll put it with the 'once you know how' and I'm sure I'll get the hang of it. Hey, your source has been blocked, could you zip it please? Thanks heaps, you've been great.
Oh, I forgot to say that under the Debug -> Exceptions, are you refering to the 'thrown' check box or the 'user-handled' check box associated with the CLR Exceptions tree?
-- modified at 15:05 Wednesday 14th February, 2007
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Ok, zipped, same location[^] but .zip on the end, thanks for finding that out about the .cs extensions, never knew about that.
Best way to think of delegates is to just treat them as variables, they're nothing more anyway.
The checkbox is thrown, it helps a lot because the debugger will break when an exception is thrown rather than when it is not handled, e.g. if you've got a try / catch block normally it'd pass through and execute the catch, but with this it breaks on the exception inside the try allowing you to find the source of the problem.
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Great info about the exception I'll give it a crack now, and check out your helper class. Super! 
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Let me know if it's successful.
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I have an error when I compile. This is the code I updated:
<br />
private void _sp_DataReceived(object sender, SerialDataReceivedEventArgs e)<br />
{<br />
InvocationHelper.Invoke(this.ChangeValue);<br />
}
Argument '1': cannot convert from 'method group' to 'System.Delegate'
P.S If you prefer to have a fiddle yourself I can send you the source. Thanks for being so helpful.
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Oops, forgot the delegate bit 
private delegate void ChangeValueDelegate();
private void _sp_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
InvocationHelper.Invoke(new ChangedValueDelegate(this.ChangeValue));
}
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Dang, didn't work. Does the block:
singleCastDelegate.DynamicInvoke(arguments);
Mean that it's not cross threaded?
Curiously though, after I use your class then click on the button to change the value (just to see if it still works) it doesn't update the value in the label anymore...
P.S I had to put a check in your code as I was getting an error
if (arguments != null) <- here<br />
{<br />
if (requiredParameters != arguments.Length)<br />
....<br />
}
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Yes it's not cross-threading, I had a proper look through your code and now understand exactly what you're trying to do.
Did you change the code in the button's event handler? That can stay the same, it's only the SerialPort stuff because of the way that Windows uses a seperate thread to read data internally.
Re: error, you can actually scrap the first "wrapper" method completely, it's not needed at all (in fact I don't know why it's there at all), if it wasn't there then you wouldn't need your check because of the params declaration the arguments array would be zero length as opposed to null  .
Try setting a breakpoint on the line including the ChangeValue inside the DataReceived handler, if that's hit then all handlers are setup properly for the SerialPort, then try F11 (in standard edition anyway) to do Debug -> Step Into, the debugger should then jump to the ChangeValue routine. Just step through the code and examine the variables to see if anything untoward is happening.
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