test script for detecting KeyDown event for arrow keys on MdiChild Form.

mditest.boo

import System
import System.Windows.Forms;

class Parent(Form):
  public def constructor():
    self.IsMdiContainer = true
    _btn = Button(Text: "Create Child")
    _btn.Click += self.CreateChild
    self.Controls.Add(_btn)

  _btn as Button
  _i = 0

  private def CreateChild():
    c = Child(Text: "child$_i", MdiParent: self)
    c.Show()
    ++_i

class Child(Form):
  public def constructor():
    _lbl = Label(Text: "TEST")
    _lbl.Dock = DockStyle.Bottom
    _lbl2 = Label(Text: "TEST2")
    _lbl2.Dock = DockStyle.Bottom
    _lbl3 = Label(Text: "TEST3")
    _lbl3.Dock = DockStyle.Bottom
    self.Controls.Add(_lbl)
    self.Controls.Add(_lbl2)
    self.Controls.Add(_lbl3)
    self.KeyDown += {o,e|_lbl.Text = "kd: $o: ${e.KeyCode}"}
    self.Load += self.OnLoad

  _lbl as Label
  _lbl2 as Label
  _lbl3 as Label

  private def OnLoad(sender, e):
    self.MdiParent.PreviewKeyDown += self.OnParentPreviewKeyDown // * 1.
    self.PreviewKeyDown += self.OnPreviewKeyDown

  // * 1.  MDI親WindowのPreviewKeyDownにつなげても呼び出されない
  private def OnParentPreviewKeyDown(sender, e as PreviewKeyDownEventArgs):
    _lbl2.Text = "pkd(p): ${sender}: ${e.KeyCode}"
    if e.KeyCode == Keys.Right or e.KeyCode == Keys.Left:
      e.IsInputKey = true

  private def OnPreviewKeyDown(sender, e as PreviewKeyDownEventArgs):
    _lbl3.Text = "pkd(c): ${sender}: ${e.KeyCode}"
    if e.KeyCode == Keys.Right or e.KeyCode == Keys.Left:
      // IsInputKey が true であれば KeyDown eventが発生する
      e.IsInputKey = true

[STAThread]
public def Main(argv as (string)) as void:
  Application.EnableVisualStyles()
  Application.SetCompatibleTextRenderingDefault(false)
  Application.Run(Parent(Text: "parent"))