I have a user that is currently running my Winforms app on Win7. My app allows users to select rows from an open Excel spreadsheet and drag-n-drop them onto the app. However, this user cannot do the drag-n-drop. The cursor changes to the "no" cursor (little circle with line through it) and the operation won't complete.
I was researching drag-n-drop and Win7 and everything I found points to UAC and/or UIPI. I was looking for some solutions and am not sure if any of the below would work:
If the user logs in as admin (and as a result runs my app as admin) would that allow drag-n-drop to work?
Does the user need to turn off or change the settings of UAC/UIPI in order to be able to drag-n-drop?
I am not sure what the issue is. My app usually runs from C:/Documents and Settings/... (C:/Users/... on Win7). Does where it is running from matter? Does drag-n-drop not work because the user is not running my app with enough permissions? Are his Excel and my app on different permission levels? If so, what can be done about that? Note that even though my app allows users to just drag the file directly, that doesn't work either.
Also, is there any way I can have the user reproduce this issue with other apps? Are there apps that come with Win7 that he can see the same problem with. For example, can this be reproduced using Notepad?
Thanks.
Explaining this problem away by UIPI is a very long stretch. It doesn't have anything to do with whether or not the user is logged-in as an admin, that doesn't affect UAC and your program will be running with that same account anyway. The only way UIPI could kick in to stop a D+D is when your program is elevated and Excel is not.
To get yourself elevated requires work and doesn't happen by accident. You'd have to include a manifest so that the user gets the UAC prompt, you'd know about that. Or the user would have to change the desktop shortcut and tick the "Run this program as an administrator" option, she's know about that. While UIPI can be bypassed for Windows messages (ChangeWindowMessageFilter), it cannot for Drag and Drop so if any elevation is going on then your stuck. The ultimate test is to simply ask the user to put the UAC slider all the way down.
The much more likely scenario is that your DragEnter event handler simply isn't happy with the data it sees and therefore doesn't assign the e.Effect property. If you can't get a debugger on-site then write a little test program that logs the values of e.Data.GetFormats() plus whatever else you use to check if the drop is acceptable. And don't forget the obvious: the user simply fumbling the drag somehow.
Related
I have a sandbox system redirecting file modifications by hooking Ntxxx file system APIs. An interesting thing is, if i move files in Notepad->File/Open dialog in my sandbox, e.g. from desktop\a.txt to desktop\b\a.txt, the a.txt file on real desktop just disappears, and it comes back after i refresh real desktop by pressing F5. actually there is no change in desktop folder at all, because all changes are directed. I know that most apps use API like ReadDirectoryChanges to monitor changes, but apparently explorer is doing something different. I tried tools like https://directorymonitor.com/, they did not observe any changes on desktop. I guess SHFileOperation internally interact with explorer somehow, but who knows details and how can i prevent this notification? It is really strange for users to see a file disappearing while it is actually still there.
windows calls windows_storage!SHChangeNotify instead of that one in shell32. Why does Windows have two copies of same API, are they different?
I am developing a macOS app which takes control of the cursor. I am using a CGEvent Tap and I am adding some arithmetic to the CGEvents in order to offset the final mouse position. Although the app is in principle working as expected, in some cases - more specifically: when running the app with certain popular illustration software and using a stylus pen - the app is producing some flickering 'ghost' positions for the mouse at its original location. The good thing is, this problem can be resolved when running the app while being logged in as root user. I have read quite some SO posts but this particular post addresses the issue best:
https://stackoverflow.com/a/9899901/5066660
As described in this post the issue is probably:
Unfortunately, the CGEventTapCreate() doc says:
Only processes running as the root user may locate an event tap at the point where HID events enter the window server; for other users, this function returns NULL.
Well the function is definitely not returning null because the tap is in effect. Also I tried all possible combinations of arguments for that function, but they all act the same. Further down in that post it is proposed to tackle the problem as follows:
Perhaps you can spin this functionality off into a separate process that has super-user permissions, leaving the rest of your app in normal user mode? I believe there's also a way to request root permissions for just a specific action taken by your program.
Now if this is a possible solution I would love to implement it! So my question is: how? I've stumbled upon running scripts with elevated permissions, but not just CoreGraphics code as for example an CGEventTap. Is this possible? Could anybody give me an example of how this could be accomplished, or any other solution to the problem?
All help is welcome, thank you very very much.
From Apple documentation:
Event taps receive key up and key down events if one of the following conditions is true:
- The current process is running as the root user.
- Access for assistive devices is enabled. In OS X v10.4, you can enable this feature using System Preferences, Universal Access panel, Keyboard view.
So giving the the application Accessibility rights solved it for me (no need to run as admin). This can be achieved System Preferences -> Security & Privacy -> Accessibility and add you program there.
I have an application that uses COM to automate Word. It needs to run even when a user is not logged in. I achieved this on Windows 7 by making it run as a scheduled task which runs at startup and doesn't require a user to be logged on. I also had to use the 'hack' where you add a 'Desktop' folder in 'C:/Windows/SysWow64/config/systemprofile'.
I tried this same method in Windows Server 2012, but it doesn't work. I can see in the task scheduler that the application is starting an instance of Word. However, it then appears to 'hang' and nothing happens. I think perhaps the invisible instance of Word is showing an error message which causes the whole thing to hang, as I cannot dismiss the message.
Has anyone else had trouble getting COM to work on windows server? Is there any way of showing hidden instances of Word to see if an error dialog is showing? Or any other way of diagnosing what the problem is?
I know ideally we would have an app that created the word documents without using COM, but this is not an option at the moment.
Does your app work when run as a logged-in user?
In the past I've run into what sound like similar problems, when running programs that try to use COM interfaces; some tasks work, but others simply don't function unless run as a logged-in user with an interactive desktop.
For me the simplest solution was to set up the machine to log in as a user at boot (which you can set up in the control panel - or I think there might also be a sysinternals tool that supports configuring that nowadays), then make sure that task scheduler/Jenkins/whatever you use launches the app as the logged-in user.
I manage a number of Windows PCs which are used to control equipment. Each computer has a specific program installed which is what people launch to use that equipment. We want to require people to log in before they can access this program.
Currently, I have a wxpython app which just launches that executable when people log in with the correct credentials. However, you can just run the program directly and bypass logging on. I'd like to make a mock logon screen, ie, fullscreen and modal, which only goes away when you log in. Also it should not be able to be bypassed by alt-tab, windows key, etc. How might I accomplish this with wxpython?
There is no full proof way to do this on Windows. You can show a wx.Frame modally using its MakeModal() method. And you can catch EVT_CLOSE and basically veto it it they try to close the frame. However, if they have access to the Task Manager or even Run, they can probably get around the screen. Most users won't be that smart though. You can delete the shortcuts to the apps you want to launch with wx and that will force most normal users to use your login screen. It's only the smart ones who like to troll through the file system who will go around it.
I'm trying to figure out if there's a way to use SetWindowsHookEx and be able to affect apps that are run with Admin rights on Vista, with UAC enabled. This is an app that will need to add a small button to the caption bar of other windows to enable some multi-monitor-aware handling. I would have thought this couldn't be done, but I've seen one app that appears to do this. As far as I can tell, this other apps is not being run with Admin rights, and yet it can affect all apps in the system, including those with Admin privilege.
It would seem that there's a way to do this, then, but I'm at a loss on how. My app only needs to be able to draw on window title bars and be able to affect their movement and size. I don't need to do anything else.
You can't, as administrative processes are isolated from non-administrative processes running on the same user desktop. You can't even drag and drop between admin and non-admin processes.
This is an in-dept analysis: http://technet.microsoft.com/en-us/magazine/2007.06.uac.aspx
About the application you are referencing, it probably uses some administrative code running in background (usually as a service) so it can interact with administrative processes.