void SetContextMenuSize()
{
if (_contextMenu.Items.OfType <ToolStripItem>().Any(item => item.Available))
{
var width = _contextMenu.Items.OfType <ToolStripMenuItem>().Where(item => item.Available)
.Max(item => TextRenderer.MeasureText(item.Text, item.Font).Width);
var height = _contextMenu.GetAvailableItems()
.Sum(item => item.Height);
_contextMenu.Width = width + 45;
_contextMenu.Height = height + 5;
}
}