How to prevent a form from being activated/gaining focus.

How to prevent a form from being activated/gaining focus.

• PauloPina

  I'm finally starting to make headway on this. I was able to get the form to not be activated when clicking on other windows except for two exceptions. I did this by setting the CreateParams with WS_EX_NOACTIVATE. That works perfectly except when:
  -I create a form and call show() from the form I don't want to be activated.
  -There are other Windows that have the TopMost property set to true.
  
  I'm mainly concerned with the first one. I have another form that I'm creating from the main form that has some buttons on it. I want this to never loose focus from clicking on the main form.
  
  I'm getting really close, I can feel it. Can anyone shed some light on this last problem
  
  Thanks everyone for the help thus far.
  
  

• Bryan Chriscoli

  I tried your suggestion with the following code:
  
  [DllImport("user32.dll")]
  static extern IntPtr SetActiveWindow(IntPtr hWnd);
  
  protected override void WndProc(ref System.Windows.Forms.Message m)
  {
  if (m.Msg == 0x001C && m.WParam.ToInt32() == 1)
  {
  SetActiveWindow(m.LParam);
  }
  else
  {
  base.WndProc(ref m);
  }
  }
  
  
  But the window isn't being reactivated. I've stepped through the code and it is getting to the SetActiveWindow call but the other form is never reactivated. Any ideas as to what I might be doing wrong
  
  I'm not at all familiar with subclassing using Windows hooks any additional info would be great.
  
  Is there some way to override the mouse down event
  
  

• Hydra20010

  You might be able to do something like this by overridding the WndProc method in the Form.

  The message you care about is WM_ACTIVATEAPP (0x001C) The WParam property in the Message is either 0 or 1 indicating deactivation or activation respectively. The LParam property contains the IntPtr identifier for the thread of the window being deactivated.

  The problem is that I think this occurs at activation and you cannot stop it from activating. However, you can use the value from LParam to reactivate the original window. I'm not exactly sure how to do that, but the SetActiveWindow API comes to mind.

  Subclassing using Windows hooks also comes to mind as a possibility. I hope this gives you enough information at least to find the answer you want.

  
  
  

• Jeff Windsor

  Panagiotis Kefalidis wrote:

  You can use the ShowWindow API.It takes a parameter called SW_SHOWNOACTIVATE which will actually show the form/window, but it will not steal focus from the active form.

  
  That only helps if you are displaying the window, that doesn't prevent the form from being activated when you click on it.
  
  

• Robert Darwin

  I found the forum that had posted a similar question. This was one of the responses:
  
  http://www.dotnet247.com/247reference/msgs/29/147917.aspx
  

  wrote:

  Dr Woo, I did a quick test and looked at the messages recieved by the OSK with Spy++. It looks like it prevents gaining focus by handling WM_MOUSEACTIVATE and returning MA_NOACTIVATE. Then it posts WM_LBUTTONDOWN and WM_LBUTTONUP messages to itself to simulate that a click took place. Mattias

  
  
  Anyone familiar with what he is talking about
  
  

• mrgilbe1

  xbrady wrote:

  Panagiotis Kefalidis wrote: You can use the ShowWindow API.It takes a parameter called SW_SHOWNOACTIVATE which will actually show the form/window, but it will not steal focus from the active form. That only helps if you are displaying the window, that doesn't prevent the form from being activated when you click on it.

  
  Oh sorry, i guess i missed the part mention that you don't want to get it activated when you click on it..
  
  
  

• jefftardif

  Thank you for the correction on my code. That did indeed work as was intended. The only problem is that it is giving the same affect as when I overrid OnActivate. This does work but I get a flickering on the other form every time I click on my window. It looks as if it is still bringing my window to the front and then immediatly bringing the other one back up in front of mine. This works but I would prefer to not have the flickering. I was reading in another forum about the same type of issue and someone said that the OSK that Windows uses does something with the mouse click events. I'll try and find the quote again.
  
  Also, PJ. van de Sande, could you please explain how this line works:
  if(((int)m.WParam & 0xFFFF) != WA_INACTIVE)
  
  I'd like to know how that works.
  
  Thanks
  
  

• smitten94

  You can use the ShowWindow API.It takes a parameter called SW_SHOWNOACTIVATE which will actually show the form/window, but it will not steal focus from the active form.
  
  
  

• BP01-SQL Admin

  Hello,

  Maybe this article can help you:

  Use .NET Forms as Popup Windows
  http://www.vbaccelerator.com/home/NET/Code/Controls/Popup_Windows/Popup_Windows/article.asp

  John.

  
  

• JonathanCox

  Try this:
  
  

  [DllImport("user32.dll")][DllImport("user32.dll")] private extern static IntPtr SetActiveWindow(IntPtr handle); private const int WM_ACTIVATE = 6; private const int WA_INACTIVE = 0; protected override void WndProc(ref Message m) { if(m.Msg == WM_ACTIVATE) { if(((int)m.WParam & 0xFFFF) != WA_INACTIVE) { if(m.LParam != IntPtr.Zero) { SetActiveWindow(m.LParam); } else { // Could not find sender, just in-activate it. SetActiveWindow( IntPtr.Zero ); } } } base.WndProc(ref m); }

  
  
  
  
• How to prevent a form from being activated/gaining focus.