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Capturing Window Controls and Modifying their properties

, 19 Feb 2005 GPL3
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A Spy tool program like MS Spy++ that lets you capture window controls and modify their properties. Useful for learning window handles and their properties.

Sample Image - windowspy.gif


I was interested to have a tool such as Spy++ in Microsoft Visual Studio, but I'd like that the tool can modify window controls. For instance, some times, we need to enable some inactive controls in a program during run-time. MS Spy++ does not have any facilities to do this, and so I made it by myself.

This program is useful to obtain a window handle, caption, class name, style, and size. Moreover, it facilitates changing caption name, style, and extended style of victim window control in run-time load.

The application is a Win32 project without using MFC. It hooks the target window by WindowFromPoint() user32 API. There is an algorithm to seek on child and parent window to capture child windows inside a program by using GetWindowRect() and GetWindow() in a tricky way. It applies GetWindowLong() to obtain window properties and SetWindowLong() to modify them.

Hooking target window

We can hook victim window through WM_MOUSEMOVE mouse event:

if (bSeeking)
  HWND hWindowUnderTheMouse;
  //HWND hWindowUnderTheMouseChild;
  points = MAKEPOINTS(lParam); 
  hWindowUnderTheMouse = WindowFromPoint(point);
  if(hWindowUnderTheMouse != hSeekedWindow)
    hSeekedWindow = hWindowUnderTheMouse;
    // update the twin window
  points = MAKEPOINTS(lParam); 

It seeks the correct window target by searching through its parent and its children by SeekDumpWindow() which is defined in <DumpSeek.h> inside the program.

Modifying target window

It is very easy to modify the victim window by its handle. If you have the window handle, you can obtain and change styles very easily by GetWindowLong() and SetWindowLong() and also window caption by using SetWindowText() and SendDlgItemMessage(). By looking inside UpdateFlags() in the program, you will find the code which performs this to modify the target window:

  HWND_TOPMOST, 0, 0, 0, 0,
  HWND_NOTOPMOST, 0, 0, 0, 0,
if(BACKdwID!=dwID) SetWindowLong(hHandle, GWL_ID, dwID);
if(BACKdwStyle!=dwStyle)SetWindowLong(hHandle, GWL_STYLE, dwStyle);
SetWindowLong(hHandle, GWL_EXSTYLE, dwExtendedStyle);

The code to change caption depends on the type of window control. To change caption of Edit Control and Box Control, it has to use SendDlgItemMessage() instead of SetWindowText() in other window controls:

  HWND hWndParent=GetParent(hHandle);


I hope this tool clarifies window classes and their manipulation for people who are beginners in this field. This would be an introduction to make window Spy tools and work with handles.

Eventually, I should appreciate you if you would kindly take the time to mention your ideas, suggestions, and any bugs you may find in this program.


This article, along with any associated source code and files, is licensed under The GNU General Public License (GPLv3)


About the Author

Ashkbiz Danehkar

Australia Australia
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Comments and Discussions

QuestionTo most PinmemberNguyen Luong Son20-Oct-14 2:03 
QuestionManually enter handle PinmemberNguyen Luong Son28-Aug-14 18:33 
QuestionStay on top .... PinmemberMember 51837411-Oct-13 1:41 
GeneralMy vote of 5 PinmemberYiannis Spyridakis10-May-12 2:06 
QuestionGood job! PinmemberDH00081-Mar-12 4:53 
GeneralInstance of ClassName Pinmembercharleslambert1424-Mar-11 6:12 
GeneralGreat! Pinmemberyulinxie16-May-10 5:22 
GeneralOne Pblm PinmemberNaveen.R10-Sep-07 19:23 
QuestionSpy++ PinmemberBourtree7-Mar-07 10:26 
GeneralNice article, but cannot compile with VS.Net 2005 Pinmemberyjagota18-Feb-07 10:38 
QuestionCan it capture a label in vb6 program? Pinmemberpctimhk30-Sep-06 9:24 
GeneralGoogle Earth Toolbar PinmemberTodd Wilder22-Jul-06 17:55 
GeneralExtra Ordinary PinmemberAsheshVashi9-May-06 20:56 
GeneralMsDos Pinmemberroberto1979es8-Feb-06 5:15 Pinmemberroberto1979es7-Feb-06 12:10 
GeneralRe: PinmemberAshkbiz Danehkar7-Feb-06 13:07 
GeneralRe: PinmemberTutu7-Jun-06 21:51 
Generalwindows controls PinmemberB!Z16-Jan-06 23:13 
GeneralModifing Window Title name PinmemberVitoto7-Dec-05 12:10 
GeneralRe: Modifing Window Title name PinmemberAshkbiz Danehkar7-Feb-06 13:19 
GeneralFound bug and fix - nice app Pinmemberdrudru2-Aug-05 20:54 
GeneralRe: Found bug and fix - nice app PinmemberAshkbiz Danehkar7-Feb-06 13:09 
Generalmay be a bug PinmemberAmilan29-Jun-05 7:17 
GeneralJust what I want Pinmemberispring24-Jun-05 1:30 
GeneralXP related question PinmemberCodeBuddy2612-Jun-05 8:59 
GeneralRe: XP related question PinmemberJackyFrost26-Aug-05 15:02 
GeneralPorting to WindowsCE Pinmemberhgode9-Jun-05 1:55 
GeneralRe: Porting to WindowsCE Pinmemberhgode9-Jun-05 3:40 
GeneralRe: Porting to WindowsCE Pinmemberfoobar715-Oct-05 6:57 
GeneralRe: Porting to WindowsCE PinmemberAshkbiz Danehkar7-Feb-06 13:22 
GeneralRe: Porting to WindowsCE [modified] PinmemberPrabhat.Singh30-Sep-07 2:01 
QuestionWhere is the input focus? PinmemberFree to Go21-Mar-05 10:35 
GeneralTiz the sweet nectar... PinmemberMark (Code6) Belles15-Mar-05 12:54 
Gotta give you props. 5 Stars. You beat me to the punch. lol, just this weekend I was messing around with one of my other articles, and someone wanted to do Spy++ like window finding/highlighting, so I code up that feature. To let them spy on a window, and then capture it. Since you like this sort of thing, but mine's in C#.

While I was working on it, I was looking at Spy thinking, you know, it'd be fun to make it edit the style bits of a window... and just today I stumble on your article!

I dig the MFC style property box. Good stuff. You did a better job of the cursors, I swiped them from another cursor I found on here. Pretty good stuff man, I like your style.


Si vic pacem para bellum - If you want peace, prepare for war
GeneralSend Messages plans PinmemberPeter Ritchie12-Feb-05 7:39 
GeneralRe: Send Messages plans PinmemberAshkbiz Danehkar13-Feb-05 6:59 
GeneralWell, I must say, something innovative! PinmemberPolite Programmer11-Feb-05 8:47 
GeneralRe: Well, I must say, something innovative! PinmemberThatsAlok11-Feb-05 18:54 
GeneralRe: Well, I must say, something innovative! PinmemberAshkbiz Danehkar13-Feb-05 7:19 
GeneralGreat Article! PinmemberThatsAlok10-Feb-05 19:23 
GeneralRe: Great Article! PinmemberAshkbiz Danehkar13-Feb-05 7:14 
GeneralRe: Great Article! Pinmemberf211-Apr-05 7:10 
GeneralRe: Great Article! PinmemberAshkbiz Danehkar12-Apr-05 8:00 

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