IsChild Function

Declare Function IsChild Lib "user32.dll" (ByVal hWndParent As Long, ByVal hWnd As Long) As Long

Platforms

Windows 95: Supported.
Windows 98: Supported.
Windows NT: Requires Windows NT 3.1 or later.
Windows 2000: Supported.
Windows CE: Requires Windows CE 1.0 or later.

Description & Usage

IsChild determines if a parent-child relationship exists between two windows. The possible child window must be a direct descendant of the possible parent window. For example, if the possible child window is a child of a child of the possible parent window, the parent-child relationship does not exist.

Return Value

If a parent-child relationship does not exist between the two windows, the function returns 0. If the relationship does exist, the function returns a non-zero value.

Visual Basic-Specific Issues

None.

Parameters

hWndParent: A handle to the candidate parent window.
hWnd: A handle to the candidate child window.

Example

' This code is licensed according to the terms and conditions listed here.

' Demonstrate a parent-child relationship and a non-parent-child
' relationship.  Command1, a command button on window Form1, is a child
' of Form1.  However, fellow window Form2 is not a child.
Dim result As Long  ' result of the function

' Verify that Command1 is a child of Form1.
result = IsChild(Form1.hWnd, Command1.hWnd)  ' see if Form1 is Command1's parent
If result = 0 Then
  Debug.Print "Form1 is not Command1's parent window."  ' won't happen
Else
  Debug.Print "Form1 is Command1's parent window."  ' will happen
End If

' Verify that Form2 is not a child of Form1.
result = IsChild(Form1.hWnd, Form2.hWnd)  ' see if Form1 is Form2's parent
If result = 0 Then
  Debug.Print "Form1 is not Form2's parent window."  ' will happen
Else
  Debug.Print "Form1 is Form2's parent window."  ' won't happen