Remove titlebar from window. Window process started by different user

Question

I am using this code (on windows 2003) to remove and resize window:

Process process = Process.GetProcessById(12121);

IntPtr mwh = process.MainWindowHandle;
SetWindowLong(mwh, GWL_STYLE, WS_VISIBLE);
ShowWindowAsync(mwh, 3);
SetWindowPos(mwh, new IntPtr(0), 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE | SWP_FRAMECHANGED);

And declarations:

[DllImport("user32.dll")]
private static extern bool ShowWindowAsync(IntPtr hWnd, int nCmdShow);

[DllImport("USER32.DLL")]
public static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong);

[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)]
public static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, int uFlags);

static readonly int GWL_STYLE = -16;
static readonly int SWP_NOMOVE = 0x2;
static readonly int SWP_NOSIZE = 0x1;
static readonly int SWP_FRAMECHANGED = 0x20;
static readonly int WS_VISIBLE = 0x10000000;

Everything works correct, when I am resizing window associated with process started by me. But when I want to do this with other users windows, then it does nothing. How to make it works for other users windows?

score 0 · Answer 1 · edited May 23 '17 at 11:53

0

The behavior is by design in Windows Vista and later, due to the User Interface Privilege Isolation (UIPI). You could solve it if you have access to the source code of the controlled applications.

Read this answer for more: https://stackoverflow.com/a/15445510.

edited May 23 '17 at 11:53

Community

1
1

answered Apr 01 '16 at 07:46

Francesco Martire

108
1
11

I forgot to write, that it runs on windows 2003. – resterek Apr 01 '16 at 09:11

score 0 · Answer 2 · edited May 23 '17 at 12:24

process.MainWindowHandle is a .NET concept, there is no such thing as a main window in native desktop apps and therefore might not always work correctly on other processes. You should check if mwh is IntPtr.Zero, if it is then you need to use EnumWindows + GetWindowThreadProcessId + IsWindowVisible to find the applications window.

Calling SetWindowLong(mwh, GWL_STYLE, WS_VISIBLE); on a window you did not create is not OK. You need to call GetWindowLong first the get the existing style, remove all the styles you don't want and add WS_POPUP. You might want to remove some of the extended styles as well.

Remove titlebar from window. Window process started by different user

2 Answers2