Using Create with a tree control, having problems

[Ixiterra]

I'm sure I'm missing something, but I am learning VC++ on my own here. It seems like every time I try something new, I spend 10 hours tracking down something stupid. Basically this is a button that opens up a property tree control, or dialog, I don't know. Using this here: http://www.codeproject.com/treectrl/proptree.asp

BOOL CSPec::OnInitDialog()
{
	CDialog::OnInitDialog();

	DWORD dwStyle;
	CRect rc;

	// PTS_NOTIFY - CPropTree will send notification messages to the parent window
	dwStyle = WS_CHILD|WS_VISIBLE|PTS_NOTIFY;

	// Init the control's size to cover the entire client area
	GetClientRect(rc);

	// Create CPropTree control
	Tree.Create(dwStyle, rc, this, IDC_PROPERTYTREE); //Here is the problem

	//
	// Create some tree items
	//

	// Create a root item (root items should always be CPropTreeItem object since they
	// can not have properties
	CPropTreeItem* pRoot;

	pRoot = Tree.InsertItem(new CPropTreeItem());
	pRoot->SetLabelText(_T("Properties"));
	pRoot->SetInfoText(_T("This is a root level item"));
	pRoot->Expand(); // have this item expanded by default

	// Create a static item
	CPropTreeItem* pItem;

	pItem = Tree.InsertItem(new CPropTreeItem(), pRoot);
	pItem->SetLabelText(_T("Sub Item"));
	pItem->SetInfoText(_T("This is a simple subitem"));
	
	// Create a dropdown combolist box
	CPropTreeItemCombo* pCombo;

	pCombo = (CPropTreeItemCombo*)Tree.InsertItem(new CPropTreeItemCombo(), pRoot);
	pCombo->SetLabelText(_T("Combo Item"));
	pCombo->SetInfoText(_T("This is a TRUE/FALSE dropdown combo list"));
	pCombo->CreateComboBoxBool();	// create the ComboBox control and auto fill with TRUE/FALSE values
	pCombo->SetItemValue(TRUE);		// set the combo box to default as TRUE
	return TRUE;  // return TRUE  unless you set the focus to a control
}

BOOL CSPec::DestroyWindow() 
{
	// TODO: Add your specialized code here and/or call the base class
	Tree.DeleteAllItems();
	Tree.DestroyWindow();
	return CDialog::DestroyWindow();
}

I've tried various combinations of using PostNcDestroy, delete Tree vs. DestroyWindow, etc. And all I do is get crashes on the Create line after I close the dialog and open it again. As if it's not really deleting anything or something, and it's trying to access something that doesn't exist. I don't know. This is very frustrating though. :/ Any ideas, or obvious idiocy on my part? Should I just get over it and switch to VB?

[NMTop40]

Are you creating a new instance of your dialog class each time? Dialogs are not normally closed with DestroyWindow but with EndDialog. Also when a parent window is destroyed its child windows are automatically destroyed before it, but your parent is trying to destruct its child window before it is itself being destroyed.

[Mike Harnad]

1. Have you tried stepping into the code that crashes in the debugger? Is it a crash or an Assert?

2. What version of the compiler are you using? The source for that control indicates that it was compatible for Visual Studio 6.0 and Visual Studio 2003.

[JohnCz]

Dialogs are not normally closed with DestroyWindow but with EndDialog. Also when a parent window is destroyed its child windows are automatically destroyed before it, but your parent is trying to destruct its child window before it is itself being destroyed.

That is not entirely correct. To dismiss modal dialogs, code should call EndDIalog. Modeless dialogs should call DestroyWindow from OnOK handler.

Also when a parent window is destroyed its child windows are automatically destroyed before it, but your parent is trying to destruct its child window before it is itself being destroyed.

Assuming destroying child window before parent is destroyed, should not create any problems, unless added code does something unexpected.


IxiterraConsider posting entire project. Zip only project, source and res files.