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MonoMac window closing without error

I'm just starting out with MonoMac in Xamarin Studio, and I've run into the strangest problem:
I a window with an NSButton and a NSTextField on it. By this point I've cut out the event handler on the button, so it doesn't DO anything, except highlight when I click it. The button creation code looks like this:
nsButton = new NSButton(new System.Drawing.RectangleF(0, 0, 100, 100));
nsButton.BezelStyle = NSBezelStyle.RoundRect;
nsButton.Font = NSFont.SystemFontOfSize(
NSFont.SystemFontSizeForControlSize(NSControlSize.Regular));
nsButton.StringValue = text;
...and then it gets added to the window like so:
nsView.AddSubview(control.Handle as NSView);
(because in this part of the code, control.Handle is typed as object, and nsView is the main view on the window).
All runs and works fine at first. But, if I click repeatedly on that button, eventually the window just closes. No error, no exception, and the app itself doesn't quit; menus continue to respond and cheerfully log messages when I use them. But the window is simply -- gone.
It's extremely repeatable: it happens after 21 clicks. If I add an event handler that updates the NSTextField (e.g. hello.Caption="Foo";), then it happens after 19 clicks. It doesn't matter whether I click fast or slow; it's always the same number of clicks. Note that there is no code in the project to close the window, and the window doesn't even have a close box; I know of no legitimate way to close it short of quitting the app.
I am baffled here, and don't know how to debug this further. Does Xamarin have some sort of evaluation limit that closes your windows after so-many events? Is it a framework bug? Any insight will be greatly appreciated.

But, if I click repeatedly on that button, eventually the window just
closes. No error, no exception, and the app itself doesn't quit; menus
continue to respond and cheerfully log messages when I use them. But
the window is simply -- gone.
This "disappearing without a trace" sometimes occurs when an application crashes in native code badly enough. This can occur due to bugs in the binding code or mistakes made in calling the native APIs that corrupt internal cocoa state. I believe you are using MonoMac, and that this particular issue has been fixed in Xamarin.Mac.
You can sometimes get more information from the output window or by attaching lldb to your process.

This turned out to be the same issue as this one, in a slightly different guise.
In short, I wasn't keeping a reference to the NSWindow object, but instead was letting it go out of scope. So the GUI window would stick around for a while, but eventually (after some number of events or other code creating behind-the-scenes garbage) it is noticed and disposed of by the garbage collector. The window is then torn down.
It's all perfectly reasonable once you think of it, and happens under both Xamarin and MonoMac (just at slightly different times).
The simple solution, of course, is to retain a reference to the window until you're truly done with it. Problem solved!
(And yes, I feel a bit sheepish, but hopefully this question will get found by future Mac C# developers, and save them some grief.)

Debug not stopping after form closing in Visual Studio

Visual Studio Debug does not stop when i close the form that i write in C#. How can i stop debug process when i close form. I added Application.Exit() method in the form closing event but it didn't work.
Thank you.

Try this from here
If (System.Windows.Forms.Application.MessageLoop)
{
// Use this since we are a WinForms app
System.Windows.Forms.Application.Exit()
}
Else
{
// Use this since we are a console app
System.Environment.Exit(1)
}
EDIT:
If there are running infinite threads then do
Thread myThread = new Thread(...);
myThread.IsBackground = true; //set your running thread to background
myThread.Start(...);
And you can see how to? from here

Well this will be four years too late, however, I thought I'd post this for anyone else who runs into this issue (like I just did), sorry in advance if this is pretty basic, I'm fairly new to C# so this threw me for a bit.
I had the same issue as OP where, in my FormClosing event, neither Application.Exit() or Environment.Exit(0) would end the debugger.
The thing I found was looking at the reference count above my FormClosing event, it was showing '0 references'. I had just copied and pasted the closing event from another forum so there was no event handler to actually handle the event I had created/copied.
One easy way to resolve this (besides not copy and pasting code) was to create the event handler:
First go to the 'Form1.cs [Design]' tab
Navigate to the 'Properties' box
Click on 'Events'
Find 'FormClosing' and double click that
If you had the same issue you should now be able to see that there is at least 1 reference to the event. Now when you close the form it should also stop the debugger.

I landed on this question because VS was not stopping when a debugged application was shut down.
One way to see what might be causing the ide to hang is to click on pause and on the 'Debug Location' toolbar view any threads that are still running. For me I noticed that there was still a RabbitMq context that was not disposed of. So this was the clue i needed.
After I made the code change, VS now stops it debugging session once the application exits.
I know this is not a solution that you might be expecting but finding out why applications are not exiting properly or still keeping background processes alive is a very tricky subject. The active threads drop down is the best place to look imho.

Another possibility is, that your process runs in an exception which isn´t handled correctly. I used to show exception messages in self-build dialogs, but forgot to show the created window in one case. So the program ran into the exception, created the window but just didn´t show any sign of it... so the process kept running even when I closed the application.

How to check if external WPF process or other process is done launching?

I've written a WPF/C#-based "shell" which launches WPF apps or other apps.
What would be the best method for checking if the process is finally fully launched or no longer "busy"? I've noticed that the mouse cursor for the launched process stays at the busy cursor from initial launch until I can finally see the UI for the process. Could I use User32.SetCapture API to set the mouse capture to the external process, then somehow check if the mouse cursor is the busy cursor? Or perhaps there's a mechanism in the System.Diagnostics.Process class that I'm unaware of?
As some of the launched apps are pre-compiled third-party apps, I absolutely cannot implement a mechanism in the external processes to message if it is finally ready, such as: Microsoft PowerPoint 2010 Viewer, Adobe Acrobat, or Adobe Flash Player Standalone.
I can't just check if the process has been created, because then I have a blank, unresponding window and a busy cursor. I hope to hide my WPF app the moment the external process is done launching.

The WaitForInputIdle Win32 APi function will wait until given process enters the message loop (with no input pending).
Quote: "Before trying to communicate with the child process, the parent process can use the WaitForInputIdle function to determine when the child's initialization has been completed."
You can call it via P/Invoke.

Not very cear what do you mean saying "beasy", but hear are several considerations:
There is no known (clear) way, at least that I'm aware of, that can let you do something like that. The thing is that process is perfectly isolated OS kernel citizen. So you can not write something that works for all type processes, especially if they are 3rd part binaries.
What you can try to do, is get the MainWindow of the process (if there is any), get its handle, and filter OS messages untill you get for example WM_ACTIVATED.
But even if this could work in certain situations, in others can measurably fail. For example, process loaded but the program is not active, cause for some reason License window of the application appeared.
Let's see what others suggest, in my opinion, there is no generic and no single solution to cover minority of possible cases.
Good luck

C# add-in for application (via COM) freezes when a Control is added to the form?

I am developing an extension for existing application via COM.
Current interface of the application to extend allows to create custom property windows and use them inside that application.
Now, I am using .NET for that purpose and have strange problems:
extensionForm = new Form();
extensionForm.SetBounds(0, 0, 100, 100);
extensionForm.Controls.Add(new Button());
ExApplAPI.AddCustomPropertyWindow(extensionForm.Handle.ToInt32(), "Ololo");
As you can see below, the property sheets actually get extended, but after that something strange starts to happen.
Basically, if I switch to Ololo tab, then back to any of other 3 tabs (Attributes, Drawing or Services), the application freezes. I also know that the freeze happens inside of some unmanaged code block.
Another interesting fact here is that if I don't write the extensionForm.Controls.Add(new Button()) (with or without the Suspend / Resume Layout calls), everything works fine. So, if the recently constructed form has no controls (buttons or any other) on it, it doesn't freeze.
Here is a Spy++ log on the Ololo window right before the freeze (last message is the WM_CTLCOLORBTN, right after that the application became frozen):
Combining everything together:
Freezing happens only if I switch from Ololo to some other tab and then switch to the Ololo tab again.
Freezing only happens if the integrated form has at least one control on it, forms without controls don't freeze.
Application is not running any managed code at the moment and is not spending any CPU time.
So - any ideas / similiar problems solved / etc to help me in this case?

The Win32 HWND handles for the Forms in .NET are lazy initialized.
And I think this may be a problem here.
You may argue that the handle is created in your line ExApplAPI.AddCustomPropertyWindow(extensionForm.Handle.ToInt32(), "Ololo"); due to accessing Handle property.
It is true and what documentation acknowledges.
However, it creates the handle for the Form itself, but handles for child controls (Button in this case) are not created. This can be forced by calling CreateControl method. See more documentation.
I don't know if not having a handle for button may be a cause of your problem, but this is definitely something I would investigate.
To summarize, I suggest changing your code to:
extensionForm = new Form();
extensionForm.SetBounds(0, 0, 100, 100);
extensionForm.Controls.Add(new Button());
extensionForm.CreateControl();
ExApplAPI.AddCustomPropertyWindow(extensionForm.Handle.ToInt32(), "Ololo");

Are there any exception thrown?
We had an similar behavior when using WPF and COM, it solved by calling reset double calculation by using
[DllImport("msvcr70.dll", CallingConvention = CallingConvention.Cdecl)]
public static extern int _fpreset();

It is possible that the resource handle is not right. As you mentioned this happens only when the integrated form has atleast one control in it, Ololo tab is not able to find it's resources when active again. Please try storing resource handle the first time and then restoring it everytime the tab is active.

To understand why the application hangs, there are 2 things that may help:
Can you post a stack trace of the UI thread while the application is hung?
Which thread calls your code and actually creates the windows?

Winforms application stops drawing but remains reactive to events

We have a C# .NET 3.5 UI client application that runs in a multiple monitor desktop environment (typically 4 screens) on Windows 7. Every so often, after running several of these applications, the screen stops redrawing.
Controls continue to be reactive to clicks or keypress and values can be updated programmatically, but the entire form is not redrawn to reflect any changes. For example buttons that are enabled/disabled based on state may be remain grayed out, but be reactive to clicks or vice versa. Buttons do not animate when clicked.
Workaround: minimizing and restoring the window appears to clear the problem. After this, the application begins to draw correctly.
The must frustrating aspect of this problem is that programmatically, everything appears to be running normally. No exceptions are caught in our logs. Nothing was visible in the system event logs. We have not found a way to detect this condition is happening yet.
Other miscellaneous aspects: logging uses log4net, server communication layer uses ZMQ
Update:
Calling form Invalidate() and Update() does not fix the problem.
When dragging the window between screens, it shows different values on each screen.
Minimize/restore still resolves the issue.

I can't be sure of anything without seeing the app and the code, but my best guess is someone calls .SuspendLayout() before a complicated update, and an exception (probably swallowed) prevents the code from ever reaching the corresponding .ResumeLayout(). To test this, try adding a button that calls .ResumeLayout() for the form.

It seems the solution is there:
1) http://blogs.msdn.com/b/alejacma/archive/2009/08/11/controls-won-t-get-resized-once-the-nesting-hierarchy-of-windows-exceeds-a-certain-depth-x64.aspx
2) http://support.microsoft.com/kb/2664641/en-us