ReadProcessMemory Keeps Returning 0 - Error: INVALID WINDOW HANDLE
Dec 6, 2008
I'm currently developing a little hobby project to display health information in a game on my G15 keyboard through VB.NET. When I use ReadProcessMemory via an API call, it keeps returning zero. The MSDN documentation referred me to use the Marshal.GetLastWin32Error() call to find out what is wrong and it returns 1400: INVALID WINDOW HANDLE.
I am now confused about whether the first argument of the function wants a window handle or a process id. Regardless, I have tried both with FindWindow and hardcoding the process id while the application is running (getting it from task manager). I have tried three different games, Urban Terror, Grand Theft Auto: SA and 3D pinball for windows, getting the memory addresses from an application called Cheat Engine; they all seem to fail. [Code]
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Apr 12, 2009
let me show you my code first and then explain my problem.
[Code]...
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May 21, 2010
There are three forms on this application and they are a MDI Frame(frmMain) and two child forms (frmSearchEmp, frmEmpDetail).
What I am trying to do is opening a "frmEmpDetail" by executing "CallEmpDetail()" on "frmSearchEmp".[code]....
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Sep 14, 2011
I've a little program that has got tabControl with 2 tabs - "results" and "log". My idea was that when an error occurs the tab will switch automatically on tbLog to show what the problem was. Most arguably the problem is in threading. This is the code that..I use:
Dim thread As New Thread(AddressOf ExecuteQuery)
thread.Start()
ExecuteQuery executes the query and I'm making an error deliberately to see if I'll be automatically switched to the log tab which is in Try-EndTry procedure:
tbGrid.SelectedTab = tbGrid.TabPages(1)
The program indeed switches to tabLog (which is number 1) but I don't see any controls on it (txtLog), then when I'm trying to switch tabs a couple of times I get "Error creating window handle in a thread". I read other forum threads about it where people as how many controls do they have in their programs but my program does not exceed 70 controls on a form.
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Sep 3, 2009
I am using a Thread object to perform a function. This function performs a task and displays its progress in the gridview (like adding rows changing text etc )
The reason I am using a thread for this function is that there is a cancel button on the form. While the task is in progress, user can click on cancel to abort it.
Private Sub BtnStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnStart.Click m_Thread = New System.Threading.Thread(AddressOf myfunction) m_Thread.Start() End Sub
The function works fine and thread is completed. But calling any method of datagridview after thread is completed ( outside the worker thread ) generates an error- "Error creating window handle".
That's probably because i am not using the invoke method of datagridview for calling its methods or readingwriting properties Do i have to create separate delegates for all the methods properties used in the function ( worker thread)
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Jul 14, 2012
I'm in the process of converting a VB6.0 application to VB.Net (2008 Express). I have a MDI parent form, I'll call mdiBackground, and 4 MDI child forms, frmStatus, frmShow, frmQwerty, and frmSentence.The layout is as follows:mdibackground - has the menus at top and is a container for the child forms.frmSentence - appears at the top frmShow & frmQwerty - appear at the left and when one is closed the other one is in the same position.frmStatus - appears at the right, it has buttons which control when frmShow and frmQwerty are to appear I have a couple of regular forms that act as dialog forms. The Me.Close() works fine on these.
[Code]...
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Jan 10, 2012
We have a VB 2008 Windows application that is deployed on several hundred computers. For some strange reason only 2 computers out of the hundreds are experiencing the "Error creating Window handle" error. It is happening more consistantly on one machine than the other. Any idea what might be causing annoying error on such a limited basis? (It's a Windows XP machine that it is happening on. That's all the info I know regarding the machine currently.)
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Mar 20, 2010
I am trying to find the handle of the child window for the Yes button in the User Account Control window so i can click it. This window has a structure with a few child windows with the same name.
Dim hwnd As IntPtr = FindWindow(Nothing, "User Account Control")
Dim hwnd2 As IntPtr = FindWindowEx(hwnd, 0, "DirectUIHWND", vbNullString)
Dim hwnd3 As IntPtr = FindWindowEx(hwnd2, 0, "CtrlNotifySink", vbNullString)
Dim hwnd4 As IntPtr = FindWindowEx(hwnd3, 0, "Button", "&Yes")
There are multiple CtrNotifySink with its own Button child window or other child windows. How do i search thru the different CtrNotifySink window to find the one that contain the Yes button so i can send a click to it? I do need to find it before i can send a click, right? because i try just sending it to the main window with sendmessage and nothing happen.I even try sending it directly to the handle found by spy++ of the yes button with bm click but nothing happen?
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Nov 23, 2009
I am using VB.Net code to print barcode label in Zebra TLP 2844 printer. And the printer is connected to system by USB port. When i execute the code i get an error "Invalid Parameter : Name handle" in the line outFile = New FileStream(_SafeFileHandle, FileAccess.Write) . As this is a USB port So i shared the printer and used the UNC path. But still i get the error. Below is the complete code
[Code]....
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Aug 4, 2010
unhandled exception has occurred in your application. if you click continue, the application will ignorethis error and attempt continue. If you click quit, the application will close immediately"error creating window handle"What is this and how do I get rid of it?
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Dec 27, 2011
I have a relatively simple VB.NET app. It targets framework 2.0 from Visual Studio 2010. The app works fine most of the time, except that the users sometimes receive the
following exceptions. The error is completely random and somewhat rare. I haven't been able to trap it while in a development environment. It also doesn't appear to be
pointing at my code. My app continues to run if the users ignore the error. How would I trap and handle this error?
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Aug 21, 2010
How can I get the handle of the window that is below (or behind, whatever you call it) the foreground window?
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Mar 10, 2011
how do I handle the errors that may appear from the user of my program. For example, I have an triangle area program in wich I ask the user of the program to insert the length of the base and height of the triangle in a textbox. But what if he inserts a letter or something else, like a sign....my program will crash...
I know that one method would be to use On Error GoTo but I don't know how. If maybe you can direct me to some link or you could explain how do I handle errors, I would be grateful. Maybe you can even show me other ways to avoid errors from the user input.
This is my small program so far:
Private Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs)
Handles Button1.Click
Dim , Height, ARIA As Integer
[Code]....
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Jul 18, 2010
In my VB.net Winforms application I'm using the ITaskbarList3::SetOverlayIcon interface to set status overlays on the application's taskbar button (under Windows 7). This all seems to work fine for me, with the icons being shown and removed correctly.From the form load event, one of my functions makes the callSetOverlayIcon(parentForm.Handle, IntPtr.Zero, String.Empty)(where parentForm is the form which the load event has fired for) which very occasionally (on other people's machines) throws the following exception:
System.Runtime.InteropServices.COMException (0x8007057A): Invalid cursor handle. (Exception from HRESULT: 0x8007057A)
at MyNamespace.TaskbarNotify.ITaskbarList3.SetOverlayIcon(IntPtr hwnd, IntPtr hIcon,
[code].....
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Nov 2, 2011
Why does SetOverlayIcon throw an 'Invalid cursor handle' COMException occasionally
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Aug 27, 2010
I have a filesystewatcher object. On it`s event it runs a procedure which fills a treeview with a data. I had problems with treeview methods, but when I run them using invoke method everything is ok. But I still have one problem. When I load the form for the first time, everything works fine. But, when I then close the form (me.dispose, me.close), and load it once again, when Filesystemwathcer start the procedure i have an exception "invoke or begininvoke cannot be called on a control until the window handle has been created" trying to run a treeview.invoke method?
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Apr 20, 2011
I'm making a game that makes use of Control.MouseButtons and GetActiveWindow() like so:
Private Declare Auto Function GetActiveWindow Lib "user32.dll" () As IntPtr
Public Sub GetMouseState(ByRef x As Integer, ByRef y As Integer, ByRef lButton As Boolean)
Dim p As Point = Parent.PointToClient(Windows.Forms.Cursor.Position)
x = p.X
[code]....
Does GetActiveWindow() not return the correct value only when my game is running?
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Oct 12, 2011
I have a funtion that returns a generated PDF file but the problem is it shows it in the current browser window... I need for it to open in a new window. I dont see how I can pass it into a view for displaying where I could simply use target: _blank.
Function showUserPDF(ByVal pdfName As String) As ActionResult
Dim _fileName As String = pdfName
Dim _path As String = Path.Combine(AppDomain.CurrentDomain.BaseDirectory) +
[Code].....
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Sep 30, 2011
I am writing a custom application for IMAIl express 11.5 using IMAIl Server API for .Net
I am using the following code:
Dim DomData As New DomainData()
DomData.Aliases = "TestALias"
[code].....
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May 20, 2009
I am trying to get the handle of a window to get it's title text. I tried the WindowFromPoint, but it will get any control, not just a window. How do I get the window that the mouse is over?
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Apr 27, 2011
If you open several FullTilt games table, you can see that when on a table is required action it jumps automatically in foreground, BUT WITHOUT TO BE ACTIVATED, so that it title bar is grey and not blue. The window is the top window for my eyes, but it is not active.Now the question is: how to get the Hwnd of the topt VISIBLE desktop window (the window that is over all the other windows), also if it is not the active window?I can't use the GetForegroundWindow Api, becouse it gives the Hwnd of the top ACTIVE window...
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Aug 22, 2010
I have a handle to a window using the FindWindowA() function in the User32.dll (Windows API) and I would to get focus on that window at a later time in my program. how to do that with either a .NET function or User32.dll function? Is there a totally .NET way to get the window handle and focus?
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Mar 1, 2012
<DllImport("user32.dll", SetLastError:=True)> _
Private Shared Function SetActiveWindow(ByVal hWnd As IntPtr) As IntPtr
End Function
[Code]......
I'm trying to make use of some functionality from an external app in my program.
My problem is this:
My program manages to start the external app correctly and I can even get the WinHandle correctly if I don't use "ProcessWindowStyle.Minimized" when starting the app.
If I start the app minimized, WinHandle = ProcID.MainWindowHandle returns a 0 and as I understand it, it's
because the app is hidden in the system tray.
How can I start the app minimized and then get the window's handle once it has been minimized?
I've tried various functions like FindWindow and BringWindowToTop but none of them seem to work.
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Jan 10, 2012
I am following some instructions that apparently work with vb6, but as i have downloaded the lastest version of visual studio i think its up to version 10.
The code i am trying to make work is,[code..]
I searched a bit for an equivalent.
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Jan 10, 2012
I am following some instructions that apparently work with vb6, but as i have downloaded the lastest version of visual studio i think its up to version 10.[code]The error is that hWnd is not a member of windowsapplication1.form1.
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Oct 17, 2011
I'm using a third party dll for my project and one of the function that is provided by the dll use form handle as one of the argument. But when i call the function, I'm not using any window form and it's just called from another class. So what value i should put for that argument?Here's the example of that function:
AVS_Measure (device_handle, form_handle, no_measurement)
After this function has been called, it will send message to the form_handle argument whether the measurement data is available and valid.I called this function from another class just for triggering start measurement and i have another function to retrieve the data. I do not have any form associate to it, what value i should put for this argument?
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Apr 5, 2012
I'm writing a DLL library that interfaces to a USB device using winusb in VB.NET.
Since it's a DLL, I have no window, and it's possible that users of my library will also not have a window (command line apps, for instance).
The examples I've seen that detect device attach and detach all use RegisterDeviceNotification which requires a window handle to receive the attach/detach messages at.
How do I receive these messages directly into a function without a window to get a handle from?
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Aug 1, 2011
I have the below code. When I execute this code, the handle is different between the Load event and the Shown event. I thought the handle was static for an instance of a window. What could cause the handle to change? The only other thing the form is doing is setting itself to invisible and setting the ShowInTaskbar = False in the Activated event.
[Code]...
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Jun 29, 2010
I'm using the Crystal Reports Basic for Visual Studio 2008 to print reports. I have just one user that gets periodic errors saying "The handle is invalid". If she tries printing a second time, it works just fine. I've looked over her machine and it looks like it has all the same software as everyone else, and of course it never happens when I'm around. The code I'm using is: frmPrint.LogTag1.PrintToPrinter(1, True, 1, 0) ErrorToString() only returns that one line.
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Mar 19, 2012
I am making an address book for my final project in school, and have a few questions. In my address book, there is a feature to add groups so you can sort your contacts. The problem is, the add group feature is in a different form, I tried calling a procedure from the parent form to refresh all data but it does not work.[code]
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