My App needs to get the focus when it get's called by an external tool (via an API), i know that the default is, that it should just flash in the Taskbar, but in this case this is absolutely not the behaviour that i want. In this case i try to get the focus by "this.Activate()" (C#).
This is where the ForeGroundLockTimeOut comes into play.
However, I got a little problem understanding the SystemParameterInfo SPI_SETFOREGROUNDLOCKTIMEOUT.
I know that it's used to set the ForeGroundLockTimeOut which defines how long your app has to wait until it gets the focus it requested.
(for further information the variable "val" is an IntPtr that is set to 0)
SystemParametersInfo(SPI_SETFOREGROUNDLOCKTIMEOUT,0,val,SPIF_SENDWININICHANGE + SPIF_UPDATEINIFILE);
this one will change the Registry key that that handles the timeout (HKEY_CURRENT_USER\Control Panel\Desktop\ForeGroundLockTimout)
Since this will change the behaviour of all apps, it's really the last resort to use.
Now i thought what if i don't update the registry key. So i tried this:
SystemParametersInfo(SPI_SETFOREGROUNDLOCKTIMEOUT, 0, val, 0);
However it doesn't change the behavior of my app in any way, but
SystemParametersInfo(SPI_SETFOREGROUNDLOCKTIMEOUT,0,val,SPIF_SENDWININICHANGE);
does.
What i do not understand is why this only works for my app, which is absolutely what i want, but i do not understandit .Why do i have to broadcast a change, that only works for my app, when there has been no change made to any registry key or whatsoever, and why does this work only for my app.
Note: If you want to test this behavior, test it when Visual Studio is not running, while it's running (even if this Solution is not loaded) it changes the behavior of the App into getting focus in any case.
This is not a per-app setting, it is a global system setting. There's no way to set it for just your application, so when you call SystemParametersInfo with 0 for the last parameter, nothing happens.
On the other hand, when you use SPIF_SENDWININICHANGE, the new setting gets broadcast in the form of a WM_SETTINGCHANGE message. (Which is why manually editing the registry is the wrong thing to do; always call the documented API.)
Aside from that, this code is wrong:
SPIF_SENDWININICHANGE + SPIF_UPDATEINIFILE
To concatenate two flags, you must use the boolean OR operator (|), not the addition operator (+). In this particular case, because 0x1 + 0x2 and 0x1 | 0x2 are both equal to 3, it seems to work, but that's just an accident.
The real solution to this problem needs not involve manipulating global settings (because you surely don't want to do that on client machines, even if you're OK with it on your own). You need to work with the system, rather than trying to work against it. In the system's model, the process that currently has the focus is the one with the privilege of setting/changing the focus. So there are basically three options:
Just have the external tool call SetForegroundWindow itself and pass your application's window as the parameter. This altogether avoids your app having to activate itself.
Use the AllowSetForegroundWindow function to delegate the external tool's foreground-window-setting privileges to your application. It should call this function, passing the ID of your app's process as the parameter. That way, when your app calls SetForegroundWindow, it will work as expected.
Depending on how your tool and application are designed, you could just have the external tool launch the application. Like the documentation says, if a process is launched by the foreground process, it is allowed to set the foreground window.
SPIF_UPDATEINIFILE--Writes the new system-wide parameter setting to the user profile.
SPIF_SENDCHANGE--Broadcasts the WM_SETTINGCHANGE message after updating the user profile.
Related
I want to prevent users from closing a window by Alt + F4 or by clicking the close button.
How to achieve this?
I guess the windows API can do it, but I don't have any experience, and I can't find a specific solution.
Of course, it's good to be able to implement it,don't have to use a specific API.
Background: it is very difficult to find the last place in Word after closing it for a few days. After word2013, word2013 brought with it a way to return to the previous reading position, but that thing is very unstable and often can't be saved. When word is closed, I want to stop closing and pop up a notice to remind me to add a bookmark before exiting.
EDIT: This won't work, as it turned out. At least the message hook won't work because the message is posted and not sent, and about the CBT hook I'm not sure either, and I can't test it at the moment to give an evidence-based statement. The solution is probably to subclass the window but this is also non-trivial and I can't explain it properly and with working examples right now. I can't delete this answer though because it already has a comment. See here for more info. So take it with a grain of salt. I'm turning the answer to community wiki, feel free to edit it and fix/improve the solution!
EDIT2: Seems even subclassing won't be enough because Word is doing things its own way.
You need a windows hook. Either a CBT hook or a getmessage hook will do.
You have to create a DLL for this to work. The hook handler must be located in the DLL. It must have the same bitness as Word (probably 64 Bit). Then you call SetWindowsHookEx to install a global hook.
In the hook, you will have to check whether the current action is a window-closing attempt (in a CBT hook you would check for a HCBT_SYSCOMMAND of SC_CLOSE, in a getmessage hook you would check for a WM_CLOSE message), and whether it is about a Word window (for example using the window class - not sure if it has a recognizable class, you'd have to check - or the process' executable file name which you can get using GetModuleFileName since you will run inside Word's process) and prevent the action (by returning 1 from a CBT hook or returning 0 from a getmessage hook - to allow, call CallNextHookEx).
As yolu may have noticed, MS introduced a modern kind of 'theming' in Windows 10 regarding the basic OS elements like start menu and taskbar. With newer versions, you can choose a 'light' theme as an alternative to the default black theme.
I was wondering if there is an API or hook to elegantly and (more importantly) efficiently check live for theme changes (Did not find anything in the MS docs regarding this, but often enough these gems are pretty hidden there IMHO).
Specific problem: When you have a desktop application with a system tray icon, chances are high that you designed it to be bright. Nearly all of the modern Windows icons feature such a style (simple and white, yielding good readability on the black taskbar). Now you can provide a different version in a darker style for the light theme, but how to notice when to apply this on the fly?
I'm aware of the registry key under HCU (Software/Microsoft/Windows/CurrentVersion/Themes/Personalize) which is what I'm utilizing right now. However, blindly checking for change every x milliseconds seems pretty awkward.
If no such thing is available, I'm also happy to hear some ideas for more efficient implementations of such a check.
Method 1： Use RegNotifyChangeKeyValue
Notifies the caller about changes to the attributes or contents of a
specified registry key.
Methon 2: Use WM_SETTINGCHANGE
Applications should send WM_SETTINGCHANGE to all top-level windows when they make changes to system parameters. (This message cannot be sent directly to a window.) To send the WM_SETTINGCHANGE message to all top-level windows, use the SendMessageTimeout function with the hwnd parameter set to HWND_BROADCAST.
I tend to use the second method, I have tried, and have been able to work successfully.
Minimum code example：
case WM_SETTINGCHANGE:
{
if (!lstrcmp(LPCTSTR(lParam), L"ImmersiveColorSet"))
{
//theme has been changed
}
}
The accessible objects in my custom table control are stored in a doubly linked list in the table itself (so they can be invalidated when the table window is destroyed). Right now, my WM_GETOBJECT handler contains the following erroneous code sequence (where t is the table and ta is the new accessible object):
ta->next = t->firstAcc;
t->firstAcc->prev = ta;
t->firstAcc = ta;
This is an error because when the linked list is empty, t->firstAcc will be NULL, so the second line will lead to a null pointer exception.
...except not. When Inspect.exe queries my table's accessible object, it seems to "intercept" the null pointer exception, bringing my program back to a stable state and repeating the process all over again a few times before finally giving up and just grabbing the standard accessible object instead. The program still runs and seems to run quite well!
And it's not just Inspect.exe; UI Accessibility Checker also exhibits this behavior too.
This is Inspect.exe 7.2.0.0 and UI Accessibility Checker 3.0, both running on Windows 7 64-bit. I forget if both came with Visual Studio 2013 Express for Windows Desktop or not (with one of the Windows SDKs instead). The accessible objects are MSAA IAccessible objects because Windows XP compatibility is still required.
Obviously this makes debugging bugs like this problematic. So my questions are simple:
How are Inspect.exe and UI Accessibility Checker doing this? Is it special code that they share or is there something about MSAA or OLE or COM that does this?
Is there anything I can do about this? Neither of these programs have options to turn off the behavior. Could I just get the accessible object myself (posing as a client) to test this behavior? (That would work for the top-level object, but doing thorough tests for navigation would be a bit more painful.) And if so, would I need to initialize COM (for something in the same process) or run as administrator (because of UIPI)?
Thanks.
My application is loading 3rd party DLLs, and some of this DLLs open MessageBox windows.
Is there a way for me to detect when such a window was being opened?
You'll need a CBT hook to receive a notification when a MessageBox window is displayed. You install this by calling the SetWindowsHookEx() function and specifying WH_CBT for the hook ID parameter. The hook callback function will provide you a handle to the MessageBox window, which you can then use to close it.
If you know exactly when to expect the MessageBox is being created and shown, then you can adopt a lighter and simpler approach than a global hook. This would involve calling the FindWindowEx function to get a handle to the MessageBox window, which you can likewise use to close it.
Of course, to close it properly, you will need to know which type of MessageBox it is (that is, which of the standard button choices that it displays) so that you can simulate a click of the desired button. Simply managing to get the MessageBox to disappear off of the screen without providing a valid answer is highly likely to have unexpected results in terms of the library code.
It bears explicit mention that this is really bad behavior on the part of a DLL. Unless absolutely necessary, ditch whatever 3rd party that is foisting such poorly written code upon you. If it is absolutely necessary, well then that's a red flag: work hard to eliminate it as a necessity. You shouldn't have to write and maintain gobs of code to work around their inability to get the big obvious things right.
Due to the recently added "feature" in IE8 where new windows are automatically associated with a single session, some of our code is behaving erratically.
This is because a separate app would launch a new IE window when it was activated, and once the user was finished, close the window. This worked fine in IE7 because the session information in the windows stayed separate. However in IE8, since the session is shared among IE windows, we find that the "pop up" app would corrupt the session on the first app.
I have read about the nomerge switch, so that is a workaround, but I was wondering if there was a way of working the solution into the "CreateObject" of vbscript; i.e:
Dim ieWin As Object
Set ieWin = CreateObject("InternetExplorer.Application")
Is there a way of sending parameters when calling the CreateObject function?
No, there's no way to use COM to create an IE instance that specifies this behavior (or any of the others, e.g. InPrivate, No Add-ons, etc). The only thing you can do is create an automation instance that defaults to MediumIL using the CLSID provided for that purpose. http://blogs.msdn.com/b/ieinternals/archive/2011/08/03/internet-explorer-automation-protected-mode-lcie-default-integrity-level-medium.aspx
If you have control over the web application you are loading with your IE window you can set it's session to "cookieless" (http://msdn.microsoft.com/en-us/library/aa479314.aspx) which will avoid the issues you're having with multiple instances.
The solution we ended up going with, although it's more a work around than anything else - was assigning a new url to the popped up window.
Previously, it worked as follows:
Call centre agents would be using our internal app for other duties
e.g. "http://internalsite/somepage.faces" on a day to day basis.
When they got a phone call, a third party app would fire up
"http://internalsite/customerdetails.faces". This caused the issues mentioned above.
The solution we went with:
We assigned "http://internalsite/customerdetails.faces" it's own url e.g."http://customerdetailminisite/customer.faces".
This way the call center agent could keep their main window open for other stuff and still be able to handle calls when they came in.