Примеры ошибок, обнаруженных с помощью диагностики V3087
V3087. Type of variable enumerated in 'foreach' is not guaranteed to be castable to the type of collection's elements.
FlashDevelop
V3087 Type of variable enumerated in 'foreach' is not guaranteed to be castable to the type of collection's elements. VS2005DockPaneStrip.cs 1436
private void WindowList_Click(object sender, EventArgs e)
{
....
List<Tab> tabs = new List<Tab>(Tabs);
foreach (TabVS2005 tab in tabs)
....
}