Modeless Dialogs
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If you derive your dialog class from the following tiny helper class instead of CDialog your dialog box will be "Modeless" instead of "Modal"...
class CModelessDialog : public CDialog {
public:
  CModelessDialog(                         CWnd *pParent=NULL) {}
  CModelessDialog(UINT nIDTemplate,        CWnd *pParent=NULL) {Create(nIDTemplate     , pParent);}
  CModelessDialog(LPCSTR lpszTemplateName, CWnd *pParent=NULL) {Create(lpszTemplateName, pParent);}
protected:
   virtual void OnCancel()      {DestroyWindow();}
   virtual void OnOK()          {if(UpdateData(TRUE)) DestroyWindow();}
   virtual void PostNcDestroy() {try{delete this;}catch(..){}}
};
To use this, create a normal Dialog class.
Replace all occurances of the text 'CDialog' with 'CModelessDialog' in the .cpp and the .h files.
The Dialog only needs to be created to exist, but it won't be visible unless your dialog resource has its Visible flag checked: [Properties][More Styles Tab][Visible].
The code that normally goes in OnInitDlg now goes in the constructor.
To deal with the dialog before you show it, create it, deal with it, then show it.
You can leave Visible unchecked and use 'ShowWindow(SW_SHOW);' in the constructor.
Use 'OnCancel();' to end the dialog.

To stop the Dialog being opened twice, use the following code:
// In the Header file:
  static CMyDlg* Active;

// In the .cpp file:
CMyDlg* CMyDlg::Active=NULL;

// At the beginning of the constructor code MyDlg::MyDlg():
  if(Active==NULL) Active=this;
  else {
    Active->SetActiveWindow();
    OnCancel();
    return;
  }
  ShowWindow(SW_SHOW);
  SetActiveWindow();

// At the beginning of the Destructor code MyDlg::~MyDlg():
  if(Active==this) Active=NULL;

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 (1234) Last modified: Tue, 03 Feb 2009 18:29:18 +0000