I have two different applications, both native applications written in C++Builder 2009, both MDI, and both using the same progress bar utility code. One of them properly updates the Windows 7 taskbar with its progress. The other one doesn't.
I can't find any obvious differences between the two applications. No errors are reported in the failing application: the calls to ITaskbarList3::SetProgressValue and ITaskbarList3::SetProgressState return S_OK, but nothing happens in the Windows 7 taskbar.
Are there any gotchas in getting the Windows 7 taskbar progress bar to work? Any requirements that I might be missing?
My problem was likely specific to Delphi/C++Builder and was the result of a difference in how the VCL handles its top-level window.
If Application.MainFormOnTaskBar is true, then ITaskbarList3 only works if Application.MainFormHandle is used as the HWND parameter.
If Application.MainFormOnTaskBar is false, then ITaskbarList3 only works if Application.Handle is used as the HWND parameter.
In my case, one project had MainFormOnTaskBar true, and one had it false.
I have not written an app using the Windows 7 progress bar specifically but I have written many .Net apps that require updating progress using a live animation and the biggest gotcha from my experience was being sure you were updating the progress bar on the main thread.
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Note: this is not a newbie question
Main window of my application occasionally "freezes" with symptoms listed below. The application continues to work properly as soon as main window resized.
Debuggers, Windows Application Verifier and other tools I used revealed no problems.
What could be a reason or how can I check why the window becomes blocked from updates?
Some details:
old 32-bits c++ MFC application, worked fine for many years on many Window XP installations in 24/7 mode
the app renders some simple 2D graphics with MFC/GDI functions
on several computers under 64-bits Windows 7, very rarely (~once per month) app's main window stops updating: it looks exactly as if the app took a screenshot of client area of its main window and shows this screenshot until mail window resized
my diagnostic logs and all kind tools indicate that once frozen, internally the app works normally: it still renders updates but because of some reason Windows ignores them
application main menu opens and works properly
all drawings are made in single thread
various modal dialogs called via main menu also work properly
Notepad brought on top on my app shows properly and leaves no traces behind
Windows itself and all other application always work properly
I would think this is something related to the video card/its driver we are using (3 monitors connected to two NVIDIA NVS 300) but I don't understand why only my application is affected. Also I would love to know with what magic the resizing removes the update lock.
Update 12/9/2015:
I'm sure the drawing thread is not blocked: it is application main thread that also always properly responds to mouse clicks, menu commands and keyboard
All counters (memory, processor, GDI/USER objects) indicate no problems
I have a small utility app written in Visual Basic 6 that has been happily running on XP clients for many years until recently a client who is using Windows 7 has notified and shown me that the behaviour is different.
When my VB app displays the dialog, it remains hidden until the user clicks on it in the taskbar.
I changed the code so rather than using a ".show vbModal" command, I changed to displaying the form with non-modally, and then added various API calls like BringWindowToFront and SetWindowPos to make it top most AND calling .focus on the form, despite these extra instructions the best result I can achieve is to make the form flash prompting the user to click on it.
No matter what I've tried I cannot make the window display topmost, and with focus, without user intervention.
Note. this is an ActiveX exe project and is being called by a Win16 app through COM.
Has anyone else encountered this behaviour and know of a solution?
Any suggestions/advice appreciated, thanks.
Applications can't (without lying to Windows) steal focus. The calling app should really call AllowSetForegroundWindow() (if it's available on win16) to allow the COM process to steal the focus, or call SetForegroundWindow() itself.
See the help for SetForegroundWindow() for the conditions on setting focus.
I want to get the window handle of some controls to do some stuff with it (requiring a handle). The controls are in a different application.
Strangely enough; I found out that many controls don't have a windows handle, like the buttons in the toolbar (?) in Windows Explorer. Just try to get a handle to the Folder/Search/(etc) buttons. It just gives me 0.
So.. first question: how come that some controls have no windows handle? Aren't all controls windows, in their hearts? (Just talking about standard controls, like I would expect them in Windows Explorer, nothing customdrawn on a pane or the like.)
Which brings me to my second question: how to work with them (like using EnableWindow) if you cannot get their handle?
Many thanks for any inputs!
EDIT (ADDITIONAL INFORMATION):
Windows Explorer is just an example. I have the problem frequently - and in a different application (the one I am really interested in, a proprietary one). I have "physical" controls (since I can get an AutomationElement of those controls), but they have no windows handle. Also, I am trying to send a message (SendMessage) to get the button state, trying to find out whether it is pushed or not (it is a standard button that seems to exhibit that behaviour only through that message - at least as far as I have seen. Also, the pushed state can last a lot longer on that button than you would expect on a standard button, though the Windows Explorer buttons show a similar behaviour, acting like button-style checkboxes, though they are (push)buttons). SendMessage requires a window handle.
Does a ToolBar in some way change the behaviour of its child elements? Taking away their window handle or something similar? (Using parent handle/control id for identification??) But then how to use functions on those controls that require a windows handle?
If they don't have a handle, they're not real controls, they're just drawn to look like controls.
But of course, the toolbar buttons in Windows Explorer do have window handles, they're part of a toolbar. Use the toolbar manipulation functions to interact with them, not EnableWindow.
Or, better yet, use the documented APIs for things like search. Reverse-engineering Windows Explorer has never ended well for anyone, least of all the poor Windows Shell team, saddled with years of backwards-compatibility hacks for certain developers who thought that APIs are for everyone else. Whatever you do manage to get to work is very likely to break on the next version of Windows.
The controls you are talking about are using the ToolbarWindow32 class. If you want to interact with them then you'll need to use the toolbar control APIs/message. For example for enabling buttons you'd want to use TB_ENABLEBUTTON.
You can implement the controls yourself using GDI, OpenGL or DirectX. Try Window Detective on Mozilla Firefox and you will see that there is only one window. Controls in dialog boxes are not windows known to Windows.
I have a VB6 executable we use as a Starter executable for our real program.
The problem is that windows 7 shows a new icon in the taskbar for the new process, instead of the one i clicked on to start my program (of course, because the starter exe has already ended, and the new exe seems to be a new program).
Currently I use the Shell object to start the other exe. Is there a better way to do it from vb6, maybe by using a native C function with declare that does start an exe in the current process, without spawning a new process?
EDIT:
Thanks to atzz for the great information about Application Model IDs. I now have a shortcut to my app starter with a well defined id, and my app also sets the ID when started, and is now accesssible beautifully from the right icon in the toolbar. However, two problems persist:
The app is a Java App started with Exe4J, and I don't have any chance to set the AppID before Exe4J shows the splash screen, so while showing the splash screen there is a second icon in the taskbar.
If I don't manually drag my starter app icon from the Desktop to the toolbar, but instead use my apps icon and set it to be "sticky", the real app is sticked, and not the launcher.
Both problems would be beautifully solved if my launcher would start the app from within its own process. I heard something of using exec() instead of fork() for linux programs to achive this... is there something similar for windows?
I believe there is a way to accomplish what you need via Windows 7 taskbar API, though I never did it myself and thus don't remember clearly enough what I've read on the subject. Look around the Application ID concept.
Some links:
Developing for the Windows 7 Taskbar – Application ID
Inside Windows 7 - Introducing The Taskbar APIs
If the problem is the icon, why not give both programs the same icon (and the same App.Title). Then the user won't be able to tell the difference between the two taskbar entries. Presumably they aren't both visible at the same time.
Alternatively set your starter app not to appear in the taskbar (Form property ShowInTaskbar = False in the design view)
I am debugging an application which, in its message loop, calls IsDialogMessage(). Occasionally, IsDialogMessage() never returns (where never is an interval greater than 1 hour). Based on the symbols for user32.dll available from Microsoft's symbol server, it appears to be stuck in GetNextDlgGroupItem() (or an internal variant of the same), iterating over some set of windows.
The application is multithreaded and frequently receives notification of external events, which arrive as DCOM calls. I suspect that such a call is handled incorrectly in a way that corrupts some window state. If I can learn what sort of state corruption might cause an infinite loop in IsDialogMessage(), I think I will be more easily able to identify the source of the corruption.
I know this is old, but answering for posterity since no one here mentioned it.
More than likely what is going on is trouble with the windows manager determining where to forward a message. If you have a hierarchy of windows, as you probably do, then you need to ensure that non-top-level windows that contain controls themselves must have the WS_EX_CONTROLPARENT style set. If it is a dialog, you use the DS_CONTROL style. The presence of these flags modify the behavior of IsDialogMessage; they identify a window as having its own controls which can receive focus and handle tab order, etc, rather than just being a control itself.
For example, if you have a main frame window, which has a child window with WS_EX_CONTROLPARENT, which has a child window without WS_EX_CONTROLPARENT, which has a child window that has focus, and you hit TAB, you will likely encounter an infinite loop at the same place you mention.
Setting the second child's extended style to include WS_EX_CONTROLPARENT will resolve the issue.
Are you maybe disabling controls (using ::EnableWindow()) without checking first whether that control has the focus? If yes, then the focus gets lost and GetNextDlgGroupItem() gets confused.
Another reason this can happen is if you reparent a modeless dialog. At least this can happen with wxWidgets...
I've made some investigation, trying to answer this question. But only in situation, when parent window is in native MFC project and child is a managed C# Windows Forms. If you have such situation, then you may try 3 resolutions:
Run MFC dialog message loop on Windows Forms side. Here is more info: Integrate Windows Forms Into Your MFC Applications Through C++ Interop
Create 2 threads: one for Windows Forms dialog and one for native dialog. Here you can create dialog in Windows Forms, then with SetParent() set it's parent to native dialog. But be ware: if you add TabControl to Windows Forms, than hang with "IsDialogMessage() never return" will occur.
Make a wrapper for Windows Forms dialog to use in native project. For ex., wrapper may be WPF, see here: Windows Form as child window of an unmanaged app
I've taken information mostly from: http://msdn.microsoft.com/en-us/library/ms229600.aspx
And the temporary cure can be to change focus behavior. For example, disable them, or SetFocus() to parent or child windows only. But I strongly recommend to investigate the real reason, why IsDialogMessage() never return in your case.