>>181
(function(f){if(te.Ctrls(CTRL_TC,true).length==2){var rca=api.Memory("RECT");var rcb=api.Memory("RECT");api.GetWindowRect(te.Ctrls(CTRL_TC,true)[0].hwnd,rca);api.GetWindowRect(te.Ctrls(CTRL_TC,true)[1].hwnd,rcb);te.Ctrls(CTRL_TC,true)[rca.left<rcb.left||rca.top<rcb.top?f:f==1?0:1].Selected.Focus();}})(1);

2分割時のbottom(right), top(left)をもう少し的確に切り替えるならこんな感じかな
最終行の(1)はbottom(right)、(0)にするとtop(left)
window.open("file:///C:/Program Files/"); → Navigate("C:\\Program Files");
でよくない？