RemoveProp Function

Declare Function RemoveProp Lib "user32.dll" Alias "RemovePropA" (ByVal hWnd As Long, ByVal lpString As String) As Long

Platforms

Windows 95: Supported.
Windows 98: Supported.
Windows NT: Requires Windows NT 3.1 or later.
Windows 2000: Supported.
Windows CE: Not Supported.

Description & Usage

RemoveProp removes a window property from a window. This property must have been previously set using the SetProp function. Your program must remove all window properties it creates before the window they are attached to closes. However, never remove any window properties not created by your program. Although this function deletes the property itself, it does not affect the data referenced by the property in any way.

Return Value

If an error occured, the function returns 0. If successful, the function returns a handle to the data which was attached to the property. The program is then responsible for deallocating this data, if necessary.

Visual Basic-Specific Issues

None.

Parameters

hWnd: A handle to remove one of the window properties of.
lpString: The name of the window property to remove.

Example

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

' Set the "LookupFile" property of window Form1 to a string.
' This example also shows how to remove the property.
Dim hStr As Long, pStr As Long  ' handle and pointer to the string
Dim thevalue As String  ' the string referenced by the handle
Dim retval As Long  ' return value

' Set the value of the string (this could be anything, really).
thevalue = "C:\Icons\default.ico"
' Create a memory block...
hStr = GlobalAlloc(GMEM_MOVEABLE Or GMEM_ZEROINIT, Len(thevalue))
' ...and copy the string into it.
pStr = GlobalLock(hStr)  ' get a pointer to the block
retval = lstrcpy(pStr, text)  ' copy the string
retval = GlobalUnlock(hStr)  ' release the pointer

' The handle hStr now refers to a memory block holding the string.  Set
' the "LookupFile" property to this memory block.
retval = SetProp(Form1.hWnd, "LookupFile", hStr)
' Note how we cannot yet free the memory block since it is still in use.

' *** INSERT OTHER CODE (such as the GetProp example) HERE ***

' The following code releases the "LookupFile" property and frees
' the memory block to which it points.
' (this code assumes the same Dims as above)
hStr = RemoveProp(Form1.hWnd, "LookupFile")
' The property is gone; now free the memory block.
retval = GlobalFree(hStr)