private void OnClickSetOffsets(object sender, EventArgs e) { if (listView1.SelectedItems.Count > 0) { int font = (int)treeView.SelectedNode.Tag; int cha = (int)listView1.SelectedItems[0].Tag; if ((form == null) || (form.IsDisposed)) { form = new FontOffset(font, cha); form.TopMost = true; form.Show(); } } }