Splitter控件的诡异问题

[cityyokel]

navBar = new NavigateBar(Path.Combine(Environment.CurrentDirectory, "settings.xml"));
navBar.Dock = DockStyle.Left;
navBar.SaveAndRestoreSettings = true;
navBar.IsShowCollapsibleScreen = true;

verticalSplitter = new MTSplitter();
verticalSplitter.Size = new Size(7, 100);
verticalSplitter.SplitterPointCount = 10;
verticalSplitter.SplitterPaintAngle = 360F;
verticalSplitter.Dock = DockStyle.Left;

horizontalSplitter = new SplitContainer();
horizontalSplitter.Orientation = Orientation.Horizontal;
horizontalSplitter.Dock = DockStyle.Fill;
horizontalSplitter.BorderStyle = BorderStyle.FixedSingle;

// 调试了半天的结论：
// 这几个控件的添加顺序会影响最终界面的布局。
// 以下顺序可以正常显示左右竖直分割，且右边上下分割。
// 但是其他的顺序则不能正常地左右分割。
this.toolStripContainer.ContentPanel.Controls.AddRange(
    new Control[] { verticalSplitter, horizontalSplitter, navBar });