PageControlChanging (C++)
Description
This project requires a TPageControl, several TTabSheets (to add sheets, right-click the Page Control and select "New Page" from the context menu), and a TEdit control on the first tab sheet. You are not allowed to change to a new page if the active page is "TabSheet1" and there is no text in the Edit Control.
Code
void __fastcall TForm1::PageControl1Changing(TObject *Sender, bool &AllowChange)
{
if ((dynamic_cast<TPageControl *>(Sender))->ActivePage == TabSheet1)
AllowChange = (!Edit1->Text.IsEmpty());
else
AllowChange = true;
if (AllowChange == false)
{
MessageBeep(0);
Edit1->SetFocus();
}
}