ComboBox class, CB_INSERTSTRING , VB.NET and marshalling...

[GianPiero Andreis]

Hello All,
let me pose a simple question about combobox and the CB_INSERTSTRING
message.
Suppose for instance that I already have a combobox handle, how can I
declare and use the SendMessage function just for insert a new item into the
combobox ?
Of course, the combo box DO NOT belong to my process, so I can't use the
standard properties of that class.
In fact, I need to "put" a new entry in the combo box of IExplorer.
EnumWindows get me the handle of the IExplorer main window, with
EnumChildWindow s I can obtain the handle of the "www address" combo.
At this point, I would like to put into the combo an "www address" of
choice.
I tried ALL the parameters of the MarshalAs attribute related to the string,
(with the UnmanagedType enum) but never seems to works, sometime IE
crashes.. :-)

Please, don't tell to me to use SendKeys class.
..NET SendKeys class works well (do not alter, no more, the numlock and/or
capslock status of my keyboard, like the older sendkeys in VB) but I need to
use SendMessage because I want to unterstand hot to marshalling correctly
the parameters.
And last, but not least, I LIKE API's...

Thank You Gentleman for Your precious help.
Best regards
Ing. GianPiero Andreis

[CJ Taylor]

Whats your code look like for the SendMessage?

And what part are you marshalling? individual variables or an entire
structure?
"GianPiero Andreis" <le************ *@hotmail.com> wrote in message
news:uN******** ********@TK2MSF TNGP10.phx.gbl. ..

Hello All,
let me pose a simple question about combobox and the CB_INSERTSTRING
message.
Suppose for instance that I already have a combobox handle, how can I
declare and use the SendMessage function just for insert a new item into the combobox ?
Of course, the combo box DO NOT belong to my process, so I can't use the
standard properties of that class.
In fact, I need to "put" a new entry in the combo box of IExplorer.
EnumWindows get me the handle of the IExplorer main window, with
EnumChildWindow s I can obtain the handle of the "www address" combo.
At this point, I would like to put into the combo an "www address" of
choice.
I tried ALL the parameters of the MarshalAs attribute related to the string, (with the UnmanagedType enum) but never seems to works, sometime IE
crashes.. :-)

Please, don't tell to me to use SendKeys class.
.NET SendKeys class works well (do not alter, no more, the numlock and/or
capslock status of my keyboard, like the older sendkeys in VB) but I need to use SendMessage because I want to unterstand hot to marshalling correctly
the parameters.
And last, but not least, I LIKE API's...

Thank You Gentleman for Your precious help.
Best regards
Ing. GianPiero Andreis

[GianPiero Andreis]

Ok,
a piece of code...
This is the function I use for looping over the child windows in IE.
Everything works well except the SendMessageA function

Public Function EnumChildWindow sSub(ByVal argl_hChildWnd As IntPtr, ByVal
argl_Param As Integer) As Boolean
Dim lsb_ClassName As New StringBuilder(2 56)
Call GetClassNameA(a rgl_hChildWnd, lsb_ClassName,
lsb_ClassName.C apacity)
If (lsb_ClassName. ToString = "ComboBox") Then
SendMessageA(ar gl_hChildWnd.To Int32, CB_INSERTSTRING , 0,
"www.thatsite.c om")
'This just for see with Spy that the combo handle is correct
Me.Text = "I find combo with handle " &
Hex(argl_hChild Wnd.ToInt32).To String
Return False
Else
Return True
End If
End Function

And this is the prototype for the function.
Private Declare Auto Function SendMessageA Lib "user32" (ByVal hwnd As Long,
ByVal wMsg As Long, ByVal wParam As Long, <MarshalAs(Unma nagedType.LPStr )>
ByVal lParam As String) As Long

There is no need to use System.IntPtr, I don't look for system portability
at this time.

Regarding to formatted classes, at this time I don't use it because I see
Win32 APi's are working as well without the use of that encapsulation.
Maybe this is the cause of the problem, but consider that I use API very
very often in .NET (because I wrote automation programs, macro player and
so on), and everything works well without formatted classes.
I tried also the use of StringBuilder class as fouth parameter in the
SendMessageA function, but IE crashes.
If You need other informations, I would be glad to write for You forward.
Please excuse my english, is very poor, I know.

Thank You in advance, Sir.

Ing. GianPiero Andreis
"CJ Taylor" <no****@blowgoa ts.com> ha scritto nel messaggio
news:10******** *****@corp.supe rnews.com...

Whats your code look like for the SendMessage?

And what part are you marshalling? individual variables or an entire
structure?
"GianPiero Andreis" <le************ *@hotmail.com> wrote in message
news:uN******** ********@TK2MSF TNGP10.phx.gbl. ..

Hello All,
let me pose a simple question about combobox and the CB_INSERTSTRING
message.
Suppose for instance that I already have a combobox handle, how can I
declare and use the SendMessage function just for insert a new item into the

combobox ?
Of course, the combo box DO NOT belong to my process, so I can't use the
standard properties of that class.
In fact, I need to "put" a new entry in the combo box of IExplorer.
EnumWindows get me the handle of the IExplorer main window, with
EnumChildWindow s I can obtain the handle of the "www address" combo.
At this point, I would like to put into the combo an "www address" of
choice.
I tried ALL the parameters of the MarshalAs attribute related to the

string,

(with the UnmanagedType enum) but never seems to works, sometime IE
crashes.. :-)

Please, don't tell to me to use SendKeys class.
.NET SendKeys class works well (do not alter, no more, the numlock and/or capslock status of my keyboard, like the older sendkeys in VB) but I need to

use SendMessage because I want to unterstand hot to marshalling

correctly the parameters.
And last, but not least, I LIKE API's...

Thank You Gentleman for Your precious help.
Best regards
Ing. GianPiero Andreis

[GianPiero Andreis]

Hey All,
finally this code works.
I worked hard over the CB_*** messages, but there are no way (it seems to
me) to set an item into the ComboBox, like the old VB instead allow with
API.

The only solution I find is to send a message with the edit portion of the
combo (i.e. is a child window that belongs to the combo).
So You need, once You have the combo handle, to enumerate all the child
windows in the combo, and when the class name You find is "Edit", You can
send the message WM_SETTEXT with the string You wanted.
Below You find the declaration of SendMessage and the line of code that send
the string into the combo.

Hope this helps someone.

Best regards

'Declaration
Private Declare Auto Function SendMessageA Lib "user32" (ByVal hwnd As
IntPtr, ByVal wMsg As IntPtr, ByVal wParam As IntPtr,
<MarshalAs(Unma nagedType.AnsiB Str)> ByVal lParam As String) As IntPtr
'Code (argl_hChildWnd is the handle of the Edit window into the combo)
SendMessageA(ar gl_hChildWnd, New IntPtr(WM_SETTE XT), IntPtr.Zero,
"www.thatsite.c om")

[M. Angelo]

If you use sendmessage to set the strings in a list control you will not
be able to use the framework functions to retrieve it because it deals
with objects instead of strings.

The ListBox and the TextBox are not extremely difficult to subclass but
I found the ComboBox subclassing not pratical.

I would like to read further from your experience.

Regards

GianPiero Andreis wrote:

Hello All,
let me pose a simple question about combobox and the CB_INSERTSTRING
message.
Suppose for instance that I already have a combobox handle, how can I
declare and use the SendMessage function just for insert a new item into the
combobox ?
Of course, the combo box DO NOT belong to my process, so I can't use the
standard properties of that class.
In fact, I need to "put" a new entry in the combo box of IExplorer.
EnumWindows get me the handle of the IExplorer main window, with
EnumChildWindow s I can obtain the handle of the "www address" combo.
At this point, I would like to put into the combo an "www address" of
choice.
I tried ALL the parameters of the MarshalAs attribute related to the string,
(with the UnmanagedType enum) but never seems to works, sometime IE
crashes.. :-)

Please, don't tell to me to use SendKeys class.
.NET SendKeys class works well (do not alter, no more, the numlock and/or
capslock status of my keyboard, like the older sendkeys in VB) but I need to
use SendMessage because I want to unterstand hot to marshalling correctly
the parameters.
And last, but not least, I LIKE API's...

Thank You Gentleman for Your precious help.
Best regards
Ing. GianPiero Andreis