On some Windows 10 computers (and possibly older versions) there are sometimes "WorkerW" windows that show up in the list from a call to EnumWindows. This is not on all computers - just some. What are these windows and what creates them?
It is basically created by calling Shell API function SHCreateWorkerWindowW. W stands for widechar (unicode) version of the window vs. SHCreateWorkerWindowA for ascii version. Any application that needs to listen to window messages call this Api to create a worker window. The API is basically a wrapper around CreateWindowEx but with window class name that is hardcoded to "WorkerW" or "WorkerA".
Comment requested to provide supporting documentation. Unfortunately, there is no documentation on MSDN because this is an undocumented function. If you look at the disassembly of SHCreateWorkerWindowA in shlwapi.dll you can verify this easily. Alternatively, you can do a GetProcAddress() for SHCreateWorkerWindowA and call the function to create the worker window.
Related
Hello dear stackoverflow friends
A few months ago I asked you a question about QuickAccess (Pin/Unpin). Unfortunately we are still facing this issue (Unable to unpin virtual objects). After having called Microsoft Support a few times, they replied us we should subscribe to premier support... Too expensive for a small company.
So we have decided to Mimic the Windows 7 Favorites in our Shell Namespace Extension.
No big deal in the Explorer, calling ShellExecuteEx with view's handle and lnk's target object absolute pidl works like a charm.
Too good to be true, yeah, as it is not working as expected in IFileDialogs...
First the lnks (wrapped in a virtual object, but parsing name is Filesystem Path) weren't for obvious reasons shown in the dialogs. So we tried with attributes such as "SFGAO_FOLDER", "SFGAO_FILESYSANCESTOR" etc. but then the shell was calling IShellFolder's EnumObjects and that's not what we want.
So we decided to have a go with the Interface IObjectWithSite, implementing it in our Favorites' folder. We were then able to consume events from IFileDialogs such as OnSelectionChange. Then we tried the same method as in the explorer, getting view handle (first querying IOleWindow interface, getting window handle, creating view in parent IShellFolder using window handle) and calling ShellExecuteEx... And the result is.. A big application (Notepad, Word etc.) crash and a new Explorer Window with the right virtual object selected.
Probably is my approach too complicated, have you got any ideas?
Thanks a lot!
Thank to Simon, I was able to find a solution, still work in progress. The issue is that the IContextMenu, IContextMenu2 and also IContextMenu3 interfaces are implemented in the solution. On Windows 7, the .lnk menu handler was called, fine, on Windows 10 on the other hand you need to call SHCreateDefaultContextMenu, then merging the menu handlers (SHCreateDefaultContextMenu will then Call IShellFolder::GetUIObjectOf with IID_IQueryAssociations). So the code was dated... Thanks!
I have same user logged in into windows 7 station with several simultaneous sessions (like Concurrent RDP or log in at station and then via RDP).
UPDATE:
Ok, my research in this question has been stuck at this point (python example to write less complicated code):
#!/usr/bin/env python
import ctypes
import ctypes.wintypes as wintypes
def enum_desktops():
GetProcessWindowStation = user32.GetProcessWindowStation
EnumDesktops = user32.EnumDesktopsW
EnumDesktopsProc = ctypes.WINFUNCTYPE(wintypes.BOOL, wintypes.LPWSTR, wintypes.LPARAM)
hwinsta = GetProcessWindowStation()
def foreach_desktop(desk_name, lparam):
print("Desktop %s"%desk_name)
return True
EnumDesktops(hwinsta, EnumDesktopsProc(foreach_desktop), desk_lparam)
This function prints information about "Default" and "Winlogon" dektops. If we try to enumerate window stations, we'll get only "WinSta0", while I can see potentially target process started on different logon session.
So, what should I use to find window for target Desktop?
daemon is not an option at this point at all.
Have a background app or task tray applet that gets launched with every desktop session. (Easily installed by adding an EXE path to the following registry key: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\Current Version\Run).
The code that lives in that installed application will do two things:
All the desktop windows enumeration and manipulation that you need to do that can only interact with the local desktop.
Acts as a "Client" to your "server" app that runs on another desktop session. Your server app is what triggers the clients to do the window scanning. You can use almost any interprocess communication mechanism you want for this.
Already some time passed from the time the question was posted, but in case someone needs it, I will post an answer.
What you have to do is set a desktop for your current thread, which is calling FindWindow. In this way, your calling thread will operate in other desktop and will find a window. For this to achieve, you have to use SetThreadDesktop WinAPI function.
For more info, check MSDN documentation on SetThreadDesktop.
We have an application built against MFC9 (VC2008).
The application is an SDI application, and shows a file open dialog during InitInstance(). Showing that dialog causes comdlg32.dll to be loaded. Some minutes later, the comdlg32.dll is unloaded automatically. After this, the next function depending on the DLL will crash.
How can this be avoided? What governs the automatic unloading/loading of the DLL?
Further info:
We don't see this problem on WinXP with the same application.
On Win7, this behavior only occurred since the beginning of this year - maybe some MFC update is related to this?
A small test application does not exhibit the problematic behavior - the comdlg32.dll is re-loaded when needed.
We’ve found a statement by Microsoft that it isn’t recommended to use modal dialogs in InitInstance() of MDI applications (http://support.microsoft.com/kb/173261) - we have an SDI application, though.
We don't directly use comdlg32.dll in any way, only indirectly through the MFC.
You have to call InitCommonControlsEx in your application on startup.
This will initialize the comdlg32.dll and also increase the reference count of the dll, so it won't get unloaded after closing a file-open/save dialog.
You don't say whether you customize your dialog or it is just a straight up file dialog. I think starting with Vista, the common file dialog was changed some. I know if you compare older MFC code with newer, you will see that the MFC code has been changed to take advantage of those changes. For instance, the IFileDialogEvents and IFileDialogControlEvents were implemented in MFC to support the way Vista and later versions of the OS customize file dialogs.
I don't know if I have an answer, but just for grins I would probably make sure I call AfxOleInitialize() sometime in InitInstance() before I tried to call the file dialog.
The other thing I would try for sure (since it works under XP) would be in the constructor of your CFileDialog would be to make sure to set bVistaStyle to FALSE. This ensures m_bVistaStyle is set to FALSE which it is set at when running under XP.
I'm working on a little macro record/replay tool which can automate a few very old Visual Basic 6 GUIs we have. To do so, I'm identifying the controls by their name (the value of the name property of a control, that is).
One part of this tool needs to determine the name of a control given its HWND. For newer Visual Basic applications which were done using VB.NET, I can use the WM_GETCONTROLNAME window message. This works nicely.
However, this message is not understood by older windows. Is there any way to do this for controls of Visual Basic 6 applications? A solution which does not require being in the process of the GUI would be preferrable, but if I had a solution which only works inside the GUI process then that would be acceptable as well (since I can do the injection myself).
UPDATE: One thing I just tried, this moderate success: I used the AccessibleObjectFromWindow to check for implementations of the IAccessible interface of the object which shows the given HWND. In case I get an implementation (it seems that many [all?] Visual Basic controls implement this interface), I use the accName property to read out the "accessible name". Sometimes this does yield a useful string, but usually it doesn't.
I believe the only way would be getting inside the process and obtaining a pointer to the Form object, yet I have no idea how to do it from outside.
Is it possible you add support for the WM_GETCONTROLNAME to those older applications?
Or maybe, you could identify the controls by some other, natively-available properties?
Other that that, as Raymond is saying, there isn't much you can do.
Can you modify the vb6 apps? if so in each form load event you could iterate me.controls and use the SetProp(ctrl.hwnd, "MYNAME:" & ctrl.name, 0) api to add the name to the window's own property list, then in your other app you can EnumProps(ctrl_HWND) looking for the one that begins with MYNAME: and parse out the value.
I am trying to build my own little toolbox for Vista.
One of the features is a "window placeing tool" which places the windows at saved position. Another tool I could imagine are extensions to firefox or thunderbird...
For these tools to work, I need them to be able to capture "Events" in Vista.
To give you a concrete example:
Explorer Opened New Window
User started Firefox
Mouse moved
For the mouse case, there are some examples for C#.
I also know about the directory watcher, nice little helper.
Want I now need is the "new window opened event"
Any idea how to monitor this, without iterating the current window list every 5 seconds (I already know how to get Windows using the DLLImports, and getting Processes using managed code. But I have no Event when the explorer process opens a new windows)
Thanks for your help,
Chris
What you're talking about doing is not simple by any stretch.
You're going to need to register a hook, and you're going to have to build a callback procedure that gets called within another process's execution context -- this is not going to be .NET code (probably C instead), and will have to be in a DLL. That callback procedure will get called every time a certain class of events happens. It will examine the events it receives and filter out the ones you're interested, then send your application the notifications you want (probably via PostMessage). You'll then tap in to your application's main message loop to intercept those messages, and from there you can fire a .NET Event, or whatever you want.
Writing hook callbacks is tricky stuff because the code gets run within another process, not your own, and the memory management and concurrency issues take a bit of forethought. For that same reason, it's not going to be done in C#. Ideally, though, this callback code will be very small and very fast, since it's going to get called so often.
Also note that while perfectly "legal" in Win32, these system hooks have an immense amount of power and are commonly used by malware to change the way your system works. For that reason, you may run afoul of antivirus software if you attempt to do this sort of thing on a customer's computer.
Also note that the far-reaching effects of system hooks also means that simple programming mistakes can take down your whole system, which you will probably discover for yourself at some point while debugging; so save everything before you hit "run".
Good luck!
EDIT
Did a bit more search to see if there's any way to write the hook proc in C#, and came up with this:
How to set a Windows hook in Visual C# .NET
This is almost what you're looking for, but not quite. Hook procedures can either be global (which means that they run on every application) or thread (only runs within your application). The document states that:
Global hooks are not supported in the .NET Framework
Except for the
WH_KEYBOARD_LL low-level hook and the
WH_MOUSE_LL low-level hook, you cannot
implement global hooks in the
Microsoft .NET Framework. To install a
global hook, a hook must have a native
DLL export to inject itself in another
process that requires a valid,
consistent function to call into. This
behavior requires a DLL export. The
.NET Framework does not support DLL
exports. Managed code has no concept
of a consistent value for a function
pointer because these function
pointers are proxies that are built
dynamically.
Which means, again, to monitor things that go on outside your application's view, you need to set a global hook, which can't be written in .NET.
I have exactly the same issue as this, and I think I have a workable solution. Initially I looked into a similar option to the one mentioned by 'tylerl'. In my case however, instead of using 'SetWindowsHookEx', I attempted to use the similar function 'RegisterShellHookWindows'.
Unfortunately, this only succeeded in providing me with notifications of when a subset of windows are created/destroyed. The only windows which it provided notifications for are those shown on the taskbar.
Since I didn't fancy hacking into other processes, or writing the native code which would be required for SetWindowHookEx, I tried digging into the .NET automation APIs introduced in .NET 4.0, and I think this has the answer to your problem (at least as far as detecting when windows are opened / closed).
Here's a code snippet for using this API to detect windows being opened/closed:
using System.Windows.Automation;
private void StartMonitoringForWindowEvents()
{
Task.Factory.StartNew(() =>
{
AutomationEventHandler windowOpenedHandler = new AutomationEventHandler(OnWindowOpened);
System.Windows.Automation.Automation.AddAutomationEventHandler(
WindowPattern.WindowOpenedEvent, AutomationElement.RootElement,
TreeScope.Descendants, windowOpenedHandler);
});
}
private void OnWindowOpened(object source, AutomationEventArgs eventArgs)
{
try
{
AutomationElement sourceElement = (AutomationElement)source;
string message = string.Format(
"Automation.WindowOpened PID: {0}, Handle: {1}, Name:{2}",
sourceElement.Current.ProcessId,
sourceElement.Current.NativeWindowHandle,
sourceElement.Current.Name);
Debug.WriteLine(message);
// for each created window, register to watch for it being closed
RegisterForClosedWindowEvent(sourceElement);
}
catch
{
}
}
private void RegisterForClosedWindowEvent(AutomationElement element)
{
try
{
string elementName = element.Current.Name;
int processId = element.Current.ProcessId;
int nativeHandle = element.Current.NativeWindowHandle;
AutomationEventHandler windowClosedHandler = new AutomationEventHandler(
(ignoreSource, ignoreArgs) => OnWindowClosed(nativeHandle, processId, elementName));
System.Windows.Automation.Automation.AddAutomationEventHandler(
WindowPattern.WindowClosedEvent, element,
TreeScope.Element, windowClosedHandler);
}
catch
{
}
}
private void OnWindowClosed(int nativeHandle, int processId, string elementName)
{
string message = string.Format(
"Automation.WindowClosed PID: {0}, Handle: {1}, Name:{2}",
processId,
nativeHandle,
elementName);
Debug.WriteLine(message);
}
You will need to add a reference to the assemblies 'UIAutomationClient' and 'UIAutomationClientTypes'.
Here's a link to the MSDN documentation (you'll probably particularly want to take a look at the information on events):
http://msdn.microsoft.com/en-us/library/ms747327.aspx
Important implementation Notes:
1.) Notice that in the sample, I used a task factory to register for reception of the automation events. It's particularly important to avoid using the UI thread when registering for automation events or generally interacting with the automation APIs. Doing so can (and usually quickly does) result in a deadlock. Therefore, I use the task factory to ensure registration is done via the thread pool.
This also means, that the events will be received on the thread pool... So, if you need to perform any UI updates, you will have to marshal these across to the UI thread.
2.) You'll also note, that I capture any needed information on the element which may be closed, at the time of registration (using a closure). This is because, once the element is closed, we will no longer have access to this information - since the element has been destroyed.
Phil
The answer is not C# (or .Net) specific. You'll need to call SetWindowsHookEx( WH_CBT, ... ). This will allows to know when a window is created, destroyed, moved, sized, etc. You'll also need to get the relevant information from the window to identify if its one you need to do something about. Perhaps GetClassInfo, GetWindowLong, and GetWindowText.
The problem with the SetWindowsHookEx is that in order to get events from every window you need to have a separate win32 dll with the function in question exported. Although you might have success with the procedure outlined here.
To expand upon Joel Lucsy's answer, you need to use the Win32 API. However, there's a nice library, the Managed Windows API, that provides an object-oriented wrapper over common APIs. It may have what you need.