Autoit: Creating a Function? - autoit

Question

I have a GUI that records the list of all the chm in a folder. When 'RUN' button is clicked, it will open the first chm in the list until so on. Then I have created a function that should expand the tree.
My problem is my function, it works until MsgBox() and stops there. When I ran my program there is no error indicated.
#include <GuiConstantsEx.au3>
#include <GuiListBox.au3>
#include <GuiTreeView.au3>
#include <File.au3>
#include <Array.au3>
;GUI
$guiTitle = "Automation"
GUICreate($guiTitle, 250, 430)
Global $hWnd = ControlGetHandle("[CLASS:HH Parent;TITLE:AutoIt Help]", "", "[CLASS:SysTreeView32; INSTANCE:1]")
Global $hChild = _GUICtrlTreeView_GetFirstChild($hWnd, 0)
Local $source = InputBox("Source Folder","Please enter the source folder","")
;InputBox
If #error = 1 Then
Exit
EndIf
If #error = 4 Then
Exit
;GUI_List
Else
$add = GUICtrlCreateButton("Show", 10, 53, 230, 20)
$picList = GUICtrlCreateList("", 10, 78, 230, 300)
$run = GUICtrlCreateButton("Run", 170, 385, 70, 30)
GUISetState(#SW_SHOW)
While 1
$msg = GUIGetMsg()
Switch $msg
;add
Case $add
Global $FileList = _FileListToArray($source, "*.chm")
If #error = 1 Then
MsgBox(0, "", "No Files Found.")
Exit
EndIf
If #error = 4 Then
MsgBox(0, "", "No Files Found.")
Exit
EndIf
For $i = 1 To $FileList[0] ;List_IFIX Pictures
GUICtrlSetData($picList, $FileList[$i])
Next
;run
Case $run
If _GUICtrlListBox_GetCount($picList) = 0 Then
MsgBox(0, "", "No Files Found.")
Else
For $i = 1 To $FileList[0]
If Not WinExists("AutoIT Help]") Then
ShellExecute($source & "\" & $FileList[1])
_Expand($hWnd, $hChild)
EndIf
Next
EndIf
;exit
Case $GUI_EVENT_CLOSE
ExitLoop
EndSwitch
WEnd
EndIf
And here is my function:
Func _Expand($hWnd, $hChild)
WinWaitActive("AutoIT Help")
MsgBox(0,"","Expand")
While 1
$hChild = _GUICtrlTreeView_GetNextChild($hWnd, $hChild)
If _GUICtrlTreeView_GetText($hWnd, $hChild) = "Tutorials" Then ExitLoop
WEnd
_GUICtrlTreeView_Expand(ControlGetHandle("[CLASS:HH Parent;TITLE:AutoIt Help]","", "[CLASS:SysTreeView32; INSTANCE:1]"),$hchild, True)
EndFunc

Answer 1

Lots of problems with the code.
Check your titles! In two cases you have got the window title spelt incorrectly in your example. AutoIt is spelt with a lowercase t, and window title matching is case sensitive unless you set an option otherwise.
If "Tutorials" is not found then you will loop forever. You should add a check after _GUICtrlTreeView_GetNextChild to see if you've reached the end of the treeview.
But the real problem with your code is that you are setting $hWnd and $hChild at the beginning of the code, before you run the process that creates the window. As a result, the window is not found, and so $hWnd will always be NULL when you call _Expand.
This sort of question is not encouraged on stackoverflow. We like questions which will be useful to other people in the future rather than help with specific code. Before asking questions like this in the future, please try and debug the problem yourself. You could add ConsoleWrite statements through the code showing variable values, which would have shown you that $hWnd didn't have a handle value when you enter expand, from there it is obvious.