samples/htlbox/htlbox.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        htmllbox.cpp
   3 // Purpose:     HtmlLbox wxWidgets sample
   4 // Author:      Vadim Zeitlin
   5 // Modified by:
   6 // Created:     31.05.03
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) 2003 Vadim Zeitlin <vadim@wxwidgets.org>
   9 // Licence:     wxWindows licence
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 // ============================================================================
  13 // declarations
  14 // ============================================================================
  15
  16 // ----------------------------------------------------------------------------
  17 // headers
  18 // ----------------------------------------------------------------------------
  19
  20 // For compilers that support precompilation, includes "wx/wx.h".
  21 #include "wx/wxprec.h"
  22
  23 #ifdef __BORLANDC__
  24     #pragma hdrstop
  25 #endif
  26
  27 // for all others, include the necessary headers
  28 #ifndef WX_PRECOMP
  29     #include "wx/app.h"
  30     #include "wx/frame.h"
  31     #include "wx/log.h"
  32     #include "wx/textdlg.h"
  33     #include "wx/sizer.h"
  34
  35     #include "wx/menu.h"
  36     #include "wx/msgdlg.h"
  37     #include "wx/textctrl.h"
  38
  39     #include "wx/dc.h"
  40     #include "wx/icon.h"
  41 #endif
  42
  43 #include "wx/colordlg.h"
  44 #include "wx/numdlg.h"
  45
  46 #include "wx/htmllbox.h"
  47
  48 // you can also have a file containing HTML strings for testing, enable this if
  49 // you want to use it
  50 //#define USE_HTML_FILE
  51 #ifdef USE_HTML_FILE
  52     #include "wx/textfile.h"
  53 #endif
  54
  55 #include "../sample.xpm"
  56
  57 // ----------------------------------------------------------------------------
  58 // private classes
  59 // ----------------------------------------------------------------------------
  60
  61 // to use wxHtmlListBox you must derive a new class from it as you must
  62 // implement pure virtual OnGetItem()
  63 class MyHtmlListBox : public wxHtmlListBox
  64 {
  65 public:
  66     MyHtmlListBox() { }
  67     MyHtmlListBox(wxWindow *parent, bool multi = false);
  68
  69     void SetChangeSelFg(bool change) { m_change = change; }
  70     void UpdateFirstItem();
  71
  72 protected:
  73     // override this method to return data to be shown in the listbox (this is
  74     // mandatory)
  75     virtual wxString OnGetItem(size_t n) const;
  76
  77     // change the appearance by overriding these functions (this is optional)
  78     virtual void OnDrawSeparator(wxDC& dc, wxRect& rect, size_t n) const;
  79     virtual wxColour GetSelectedTextColour(const wxColour& colFg) const;
  80
  81     // flag telling us whether we should use fg colour even for the selected
  82     // item
  83     bool m_change;
  84
  85     // flag which we toggle to update the first items text in OnGetItem()
  86     bool m_firstItemUpdated;
  87
  88 public:
  89
  90     // flag which we toggle when the user clicks on the link in 2nd item
  91     // to change 2nd item's text
  92     bool m_linkClicked;
  93
  94 #ifdef USE_HTML_FILE
  95     wxTextFile m_file;
  96 #endif
  97
  98     DECLARE_NO_COPY_CLASS(MyHtmlListBox)
  99     DECLARE_DYNAMIC_CLASS(MyHtmlListBox)
 100 };
 101
 102
 103 class MyFrame : public wxFrame
 104 {
 105 public:
 106     MyFrame();
 107     virtual ~MyFrame();
 108
 109     // event handlers
 110     void OnSimpleOrCustomBox(wxCommandEvent& event);
 111     void OnQuit(wxCommandEvent& event);
 112     void OnAbout(wxCommandEvent& event);
 113
 114     void OnSetMargins(wxCommandEvent& event);
 115     void OnDrawSeparator(wxCommandEvent&) { m_hlbox->RefreshAll(); }
 116     void OnToggleMulti(wxCommandEvent& event);
 117     void OnSelectAll(wxCommandEvent& event);
 118     void OnUpdateItem(wxCommandEvent& event);
 119
 120     void OnSetBgCol(wxCommandEvent& event);
 121     void OnSetSelBgCol(wxCommandEvent& event);
 122     void OnSetSelFgCol(wxCommandEvent& event);
 123
 124     void OnClear(wxCommandEvent& event);
 125
 126     void OnUpdateUISelectAll(wxUpdateUIEvent& event);
 127
 128     void OnLboxSelect(wxCommandEvent& event);
 129     void OnLboxDClick(wxCommandEvent& event)
 130     {
 131         wxLogMessage(_T("Listbox item %d double clicked."), event.GetInt());
 132     }
 133
 134     void OnHtmlLinkClicked(wxHtmlLinkEvent& event);
 135     void OnHtmlCellHover(wxHtmlCellEvent &event);
 136     void OnHtmlCellClicked(wxHtmlCellEvent &event);
 137
 138     wxSimpleHtmlListBox *GetSimpleBox()
 139         { return wxDynamicCast(m_hlbox, wxSimpleHtmlListBox); }
 140     MyHtmlListBox *GetMyBox()
 141         { return wxDynamicCast(m_hlbox, MyHtmlListBox); }
 142
 143     void CreateBox();
 144
 145 private:
 146     wxHtmlListBox *m_hlbox;
 147
 148     // any class wishing to process wxWidgets events must use this macro
 149     DECLARE_EVENT_TABLE()
 150 };
 151
 152 class MyApp : public wxApp
 153 {
 154 public:
 155     virtual bool OnInit() { (new MyFrame())->Show(); return true; }
 156 };
 157
 158 // ----------------------------------------------------------------------------
 159 // constants
 160 // ----------------------------------------------------------------------------
 161
 162 // IDs for the controls and the menu commands
 163 enum
 164 {
 165     // menu items
 166     HtmlLbox_CustomBox = 1,
 167     HtmlLbox_SimpleBox,
 168     HtmlLbox_Quit,
 169
 170     HtmlLbox_SetMargins,
 171     HtmlLbox_DrawSeparator,
 172     HtmlLbox_ToggleMulti,
 173     HtmlLbox_SelectAll,
 174     HtmlLbox_UpdateItem,
 175
 176     HtmlLbox_SetBgCol,
 177     HtmlLbox_SetSelBgCol,
 178     HtmlLbox_SetSelFgCol,
 179
 180     HtmlLbox_Clear,
 181
 182     // it is important for the id corresponding to the "About" command to have
 183     // this standard value as otherwise it won't be handled properly under Mac
 184     // (where it is special and put into the "Apple" menu)
 185     HtmlLbox_About = wxID_ABOUT
 186 };
 187
 188 // ----------------------------------------------------------------------------
 189 // event tables and other macros for wxWidgets
 190 // ----------------------------------------------------------------------------
 191
 192 BEGIN_EVENT_TABLE(MyFrame, wxFrame)
 193     EVT_MENU(HtmlLbox_CustomBox,  MyFrame::OnSimpleOrCustomBox)
 194     EVT_MENU(HtmlLbox_SimpleBox,  MyFrame::OnSimpleOrCustomBox)
 195     EVT_MENU(HtmlLbox_Quit,  MyFrame::OnQuit)
 196
 197     EVT_MENU(HtmlLbox_SetMargins, MyFrame::OnSetMargins)
 198     EVT_MENU(HtmlLbox_DrawSeparator, MyFrame::OnDrawSeparator)
 199     EVT_MENU(HtmlLbox_ToggleMulti, MyFrame::OnToggleMulti)
 200     EVT_MENU(HtmlLbox_SelectAll, MyFrame::OnSelectAll)
 201     EVT_MENU(HtmlLbox_UpdateItem, MyFrame::OnUpdateItem)
 202
 203     EVT_MENU(HtmlLbox_About, MyFrame::OnAbout)
 204
 205     EVT_MENU(HtmlLbox_SetBgCol, MyFrame::OnSetBgCol)
 206     EVT_MENU(HtmlLbox_SetSelBgCol, MyFrame::OnSetSelBgCol)
 207     EVT_MENU(HtmlLbox_SetSelFgCol, MyFrame::OnSetSelFgCol)
 208
 209     EVT_MENU(HtmlLbox_Clear, MyFrame::OnClear)
 210
 211     EVT_UPDATE_UI(HtmlLbox_SelectAll, MyFrame::OnUpdateUISelectAll)
 212
 213
 214     EVT_LISTBOX(wxID_ANY, MyFrame::OnLboxSelect)
 215     EVT_LISTBOX_DCLICK(wxID_ANY, MyFrame::OnLboxDClick)
 216
 217
 218     // the HTML listbox's events
 219     EVT_HTML_LINK_CLICKED(wxID_ANY, MyFrame::OnHtmlLinkClicked)
 220     EVT_HTML_CELL_HOVER(wxID_ANY, MyFrame::OnHtmlCellHover)
 221     EVT_HTML_CELL_CLICKED(wxID_ANY, MyFrame::OnHtmlCellClicked)
 222
 223 END_EVENT_TABLE()
 224
 225 IMPLEMENT_APP(MyApp)
 226
 227 // ============================================================================
 228 // MyFrame
 229 // ============================================================================
 230
 231 // ----------------------------------------------------------------------------
 232 // MyFrame ctor/dtor
 233 // ----------------------------------------------------------------------------
 234
 235 // frame constructor
 236 MyFrame::MyFrame()
 237        : wxFrame(NULL, wxID_ANY, _T("HtmlLbox wxWidgets Sample"),
 238                  wxDefaultPosition, wxSize(500, 500))
 239 {
 240     // set the frame icon
 241     SetIcon(wxIcon(sample_xpm));
 242
 243 #if wxUSE_MENUS
 244     // create a menu bar
 245     wxMenu *menuFile = new wxMenu;
 246     menuFile->AppendRadioItem(HtmlLbox_CustomBox, _T("Use custom box"),
 247                               _T("Use a wxHtmlListBox virtual class control"));
 248     menuFile->AppendRadioItem(HtmlLbox_SimpleBox, _T("Use simple box"),
 249                               _T("Use a wxSimpleHtmlListBox control"));
 250     menuFile->AppendSeparator();
 251     menuFile->Append(HtmlLbox_Quit, _T("E&xit\tAlt-X"), _T("Quit this program"));
 252
 253     // create our specific menu
 254     wxMenu *menuHLbox = new wxMenu;
 255     menuHLbox->Append(HtmlLbox_SetMargins,
 256                       _T("Set &margins...\tCtrl-G"),
 257                       _T("Change the margins around the items"));
 258     menuHLbox->AppendCheckItem(HtmlLbox_DrawSeparator,
 259                                _T("&Draw separators\tCtrl-D"),
 260                                _T("Toggle drawing separators between cells"));
 261     menuHLbox->AppendSeparator();
 262     menuHLbox->AppendCheckItem(HtmlLbox_ToggleMulti,
 263                                _T("&Multiple selection\tCtrl-M"),
 264                                _T("Toggle multiple selection on/off"));
 265     menuHLbox->AppendSeparator();
 266     menuHLbox->Append(HtmlLbox_SelectAll, _T("Select &all items\tCtrl-A"));
 267     menuHLbox->Append(HtmlLbox_UpdateItem, _T("Update &first item\tCtrl-U"));
 268     menuHLbox->AppendSeparator();
 269     menuHLbox->Append(HtmlLbox_SetBgCol, _T("Set &background...\tCtrl-B"));
 270     menuHLbox->Append(HtmlLbox_SetSelBgCol,
 271                       _T("Set &selection background...\tCtrl-S"));
 272     menuHLbox->AppendCheckItem(HtmlLbox_SetSelFgCol,
 273                                _T("Keep &foreground in selection\tCtrl-F"));
 274
 275     menuHLbox->AppendSeparator();
 276     menuHLbox->Append(HtmlLbox_Clear, _T("&Clear\tCtrl-L"));
 277
 278     // the "About" item should be in the help menu
 279     wxMenu *helpMenu = new wxMenu;
 280     helpMenu->Append(HtmlLbox_About, _T("&About...\tF1"), _T("Show about dialog"));
 281
 282     // now append the freshly created menu to the menu bar...
 283     wxMenuBar *menuBar = new wxMenuBar();
 284     menuBar->Append(menuFile, _T("&File"));
 285     menuBar->Append(menuHLbox, _T("&Listbox"));
 286     menuBar->Append(helpMenu, _T("&Help"));
 287
 288     menuBar->Check(HtmlLbox_DrawSeparator, true);
 289
 290     // ... and attach this menu bar to the frame
 291     SetMenuBar(menuBar);
 292 #endif // wxUSE_MENUS
 293
 294 #if wxUSE_STATUSBAR
 295     // create a status bar just for fun (by default with 1 pane only)
 296     CreateStatusBar(2);
 297     SetStatusText(_T("Welcome to wxWidgets!"));
 298 #endif // wxUSE_STATUSBAR
 299
 300     // create the child controls
 301     CreateBox();
 302     wxTextCtrl *text = new wxTextCtrl(this, wxID_ANY, _T(""),
 303                                       wxDefaultPosition, wxDefaultSize,
 304                                       wxTE_MULTILINE);
 305     delete wxLog::SetActiveTarget(new wxLogTextCtrl(text));
 306
 307     // and lay them out
 308     wxSizer *sizer = new wxBoxSizer(wxHORIZONTAL);
 309     sizer->Add(m_hlbox, 2, wxGROW);
 310     sizer->Add(text, 3, wxGROW);
 311
 312     SetSizer(sizer);
 313 }
 314
 315 MyFrame::~MyFrame()
 316 {
 317     delete wxLog::SetActiveTarget(NULL);
 318 }
 319
 320 void MyFrame::CreateBox()
 321 {
 322     bool multi = GetMenuBar()->IsChecked(HtmlLbox_ToggleMulti);
 323
 324     if ( GetMenuBar()->IsChecked(HtmlLbox_CustomBox) )
 325     {
 326         m_hlbox = new MyHtmlListBox(this, multi);
 327     }
 328     else // simple listbox
 329     {
 330         m_hlbox = new wxSimpleHtmlListBox(this, wxID_ANY, wxDefaultPosition, wxDefaultSize,
 331                                           0, NULL, multi ? wxLB_MULTIPLE : 0);
 332
 333         // unlike wxHtmlListBox which is abstract, wxSimpleHtmlListBox is a
 334         // concrete control and doesn't support virtual mode, this we need
 335         // to add all of its items from the beginning
 336         wxArrayString arr;
 337         for (size_t n = 0; n < 1000; n++ )
 338         {
 339             wxColour clr((unsigned char)(abs((int)n - 192) % 256),
 340                          (unsigned char)(abs((int)n - 256) % 256),
 341                          (unsigned char)(abs((int)n - 128) % 256));
 342             int level = n % 6 + 1;
 343
 344             wxString label = wxString::Format(_T("<h%d><font color=%s>")
 345                     _T("Item</font> <b>%lu</b>")
 346                     _T("</h%d>"),
 347                     level,
 348                     clr.GetAsString(wxC2S_HTML_SYNTAX).c_str(),
 349                     (unsigned long)n, level);
 350             arr.Add(label);
 351         }
 352
 353         GetSimpleBox()->Append(arr);
 354     }
 355 }
 356
 357
 358 // ----------------------------------------------------------------------------
 359 // menu event handlers
 360 // ----------------------------------------------------------------------------
 361
 362 void MyFrame::OnSimpleOrCustomBox(wxCommandEvent& WXUNUSED(event))
 363 {
 364     wxWindow *old = m_hlbox;
 365
 366     // we need to recreate the listbox
 367     CreateBox();
 368     GetSizer()->Replace(old, m_hlbox);
 369     delete old;
 370
 371     GetSizer()->Layout();
 372     Refresh();
 373 }
 374
 375 void MyFrame::OnQuit(wxCommandEvent& WXUNUSED(event))
 376 {
 377     // true is to force the frame to close
 378     Close(true);
 379 }
 380
 381 void MyFrame::OnAbout(wxCommandEvent& WXUNUSED(event))
 382 {
 383     wxMessageBox(_T("This sample shows wxHtmlListBox class.\n")
 384                  _T("\n")
 385                  _T("(c) 2003 Vadim Zeitlin"),
 386                  _T("About HtmlLbox"),
 387                  wxOK | wxICON_INFORMATION,
 388                  this);
 389 }
 390
 391 void MyFrame::OnSetMargins(wxCommandEvent& WXUNUSED(event))
 392 {
 393     long margin = wxGetNumberFromUser
 394                   (
 395                     _T("Enter the margins to use for the listbox items."),
 396                     _T("Margin: "),
 397                     _T("HtmlLbox: Set the margins"),
 398                     0, 0, 20,
 399                     this
 400                   );
 401
 402     if ( margin != -1 )
 403     {
 404         m_hlbox->SetMargins(margin, margin);
 405         m_hlbox->RefreshAll();
 406     }
 407 }
 408
 409 void MyFrame::OnToggleMulti(wxCommandEvent& WXUNUSED(event))
 410 {
 411     wxWindow *old = m_hlbox;
 412
 413     // we need to recreate the listbox
 414     CreateBox();
 415     GetSizer()->Replace(old, m_hlbox);
 416     delete old;
 417
 418     GetSizer()->Layout();
 419 }
 420
 421 void MyFrame::OnSelectAll(wxCommandEvent& WXUNUSED(event))
 422 {
 423     m_hlbox->SelectAll();
 424 }
 425
 426 void MyFrame::OnUpdateUISelectAll(wxUpdateUIEvent& event)
 427 {
 428     event.Enable( m_hlbox && m_hlbox->HasMultipleSelection() );
 429 }
 430
 431 void MyFrame::OnUpdateItem(wxCommandEvent& WXUNUSED(event))
 432 {
 433     if (GetMyBox())
 434         GetMyBox()->UpdateFirstItem();
 435 }
 436
 437 void MyFrame::OnSetBgCol(wxCommandEvent& WXUNUSED(event))
 438 {
 439     wxColour col = wxGetColourFromUser(this, m_hlbox->GetBackgroundColour());
 440     if ( col.Ok() )
 441     {
 442         m_hlbox->SetBackgroundColour(col);
 443         m_hlbox->Refresh();
 444
 445 #if wxUSE_STATUSBAR
 446         SetStatusText(_T("Background colour changed."));
 447 #endif // wxUSE_STATUSBAR
 448     }
 449 }
 450
 451 void MyFrame::OnSetSelBgCol(wxCommandEvent& WXUNUSED(event))
 452 {
 453     wxColour col = wxGetColourFromUser(this, m_hlbox->GetSelectionBackground());
 454     if ( col.Ok() )
 455     {
 456         m_hlbox->SetSelectionBackground(col);
 457         m_hlbox->Refresh();
 458
 459 #if wxUSE_STATUSBAR
 460         SetStatusText(_T("Selection background colour changed."));
 461 #endif // wxUSE_STATUSBAR
 462     }
 463 }
 464
 465 void MyFrame::OnSetSelFgCol(wxCommandEvent& event)
 466 {
 467     if (GetMyBox())
 468     {
 469         GetMyBox()->SetChangeSelFg(!event.IsChecked());
 470         GetMyBox()->Refresh();
 471     }
 472 }
 473
 474 void MyFrame::OnClear(wxCommandEvent& WXUNUSED(event))
 475 {
 476     m_hlbox->Clear();
 477 }
 478
 479 void MyFrame::OnHtmlLinkClicked(wxHtmlLinkEvent &event)
 480 {
 481     wxLogMessage(wxT("The url '%s' has been clicked!"), event.GetLinkInfo().GetHref().c_str());
 482
 483     if (GetMyBox())
 484     {
 485         GetMyBox()->m_linkClicked = true;
 486         GetMyBox()->RefreshRow(1);
 487     }
 488 }
 489
 490 void MyFrame::OnHtmlCellHover(wxHtmlCellEvent &event)
 491 {
 492     wxLogMessage(wxT("Mouse moved over cell %p at %d;%d"),
 493                  event.GetCell(), event.GetPoint().x, event.GetPoint().y);
 494 }
 495
 496 void MyFrame::OnHtmlCellClicked(wxHtmlCellEvent &event)
 497 {
 498     wxLogMessage(wxT("Click over cell %p at %d;%d"),
 499                  event.GetCell(), event.GetPoint().x, event.GetPoint().y);
 500
 501     // if we don't skip the event, OnHtmlLinkClicked won't be called!
 502     event.Skip();
 503 }
 504
 505 // ----------------------------------------------------------------------------
 506 // listbox event handlers
 507 // ----------------------------------------------------------------------------
 508
 509 void MyFrame::OnLboxSelect(wxCommandEvent& event)
 510 {
 511     wxLogMessage(_T("Listbox selection is now %d."), event.GetInt());
 512
 513     if ( m_hlbox->HasMultipleSelection() )
 514     {
 515         wxString s;
 516
 517         bool first = true;
 518         unsigned long cookie;
 519         for ( int item = m_hlbox->GetFirstSelected(cookie);
 520               item != wxNOT_FOUND;
 521               item = m_hlbox->GetNextSelected(cookie) )
 522         {
 523             if ( first )
 524                 first = false;
 525             else
 526                 s << _T(", ");
 527
 528             s << item;
 529         }
 530
 531         if ( !s.empty() )
 532             wxLogMessage(_T("Selected items: %s"), s.c_str());
 533     }
 534
 535 #if wxUSE_STATUSBAR
 536     SetStatusText(wxString::Format(
 537                     _T("# items selected = %lu"),
 538                     (unsigned long)m_hlbox->GetSelectedCount()
 539                   ));
 540 #endif // wxUSE_STATUSBAR
 541 }
 542
 543 // ============================================================================
 544 // MyHtmlListBox
 545 // ============================================================================
 546
 547 IMPLEMENT_DYNAMIC_CLASS(MyHtmlListBox, wxHtmlListBox)
 548
 549 MyHtmlListBox::MyHtmlListBox(wxWindow *parent, bool multi)
 550              : wxHtmlListBox(parent, wxID_ANY, wxDefaultPosition, wxDefaultSize,
 551                              multi ? wxLB_MULTIPLE : 0)
 552 {
 553     m_change = true;
 554     m_firstItemUpdated = false;
 555     m_linkClicked = false;
 556
 557
 558     SetMargins(5, 5);
 559
 560 #ifdef USE_HTML_FILE
 561     if ( !m_file.Open(_T("results")) )
 562     {
 563         wxLogError(_T("Failed to open results file"));
 564     }
 565     else
 566     {
 567         SetItemCount(m_file.GetLineCount());
 568     }
 569 #else
 570     SetItemCount(1000);
 571 #endif
 572
 573     SetSelection(3);
 574 }
 575
 576 void MyHtmlListBox::OnDrawSeparator(wxDC& dc, wxRect& rect, size_t) const
 577 {
 578     if ( ((MyFrame *)GetParent())->
 579             GetMenuBar()->IsChecked(HtmlLbox_DrawSeparator) )
 580     {
 581         dc.SetPen(*wxBLACK_DASHED_PEN);
 582         dc.DrawLine(rect.x, rect.y, rect.GetRight(), rect.y);
 583         dc.DrawLine(rect.x, rect.GetBottom(), rect.GetRight(), rect.GetBottom());
 584     }
 585 }
 586
 587 wxString MyHtmlListBox::OnGetItem(size_t n) const
 588 {
 589     if ( !n && m_firstItemUpdated )
 590     {
 591         return _T("<h1><b>Just updated</b></h1>");
 592     }
 593
 594 #ifdef USE_HTML_FILE
 595     wxString s;
 596     if ( m_file.IsOpened() )
 597         s = m_file[n];
 598
 599     return s;
 600 #else
 601     int level = n % 6 + 1;
 602
 603     wxColour clr((unsigned char)(abs((int)n - 192) % 256),
 604                  (unsigned char)(abs((int)n - 256) % 256),
 605                  (unsigned char)(abs((int)n - 128) % 256));
 606
 607     wxString label = wxString::Format(_T("<h%d><font color=%s>")
 608                                       _T("Item</font> <b>%lu</b>")
 609                                       _T("</h%d>"),
 610                                       level,
 611                                       clr.GetAsString(wxC2S_HTML_SYNTAX).c_str(),
 612                                       (unsigned long)n, level);
 613     if ( n == 1 )
 614     {
 615         if ( !m_linkClicked )
 616             label += _T("<a href='1'>Click here...</a>");
 617         else
 618             label += _T("<font color='#9999ff'>Clicked here...</font>");
 619     }
 620
 621     return label;
 622 #endif
 623 }
 624
 625 wxColour MyHtmlListBox::GetSelectedTextColour(const wxColour& colFg) const
 626 {
 627     return m_change ? wxHtmlListBox::GetSelectedTextColour(colFg) : colFg;
 628 }
 629
 630 void MyHtmlListBox::UpdateFirstItem()
 631 {
 632     m_firstItemUpdated = !m_firstItemUpdated;
 633
 634     RefreshRow(0);
 635 }