{define-class public MyCommandButton {inherits CommandButton}
  {constructor public {default
                          label:#Label = "MyCommandButton",
                          reactive-label:#ReactiveLabel = null,
                          style:CommandButtonStyle = CommandButtonStyle.standard,
                          text-breakable?:bool = false,
                          ui-object:#CommandButtonUI = null,
                          ...
                      }
    {construct-super
        label = label,
        reactive-label = reactive-label,
        style = style,
        text-breakable? = text-breakable?,
        ui-object = ui-object,
        ...
    }
  }
}

{define-class public MyTextField {inherits TextField}
  {constructor public {default ...}
    {construct-super {splice ...}}
  }
}

And I use a DEFAULT-STYLE-SHEET that comes with style libraries. I use it as is, with no modifications. (I said I used my own style sheet, but I found the problem also shows up when I use the default.)
This is the layout code created by VLE. There are my controls and normal controls.

{define-layout-class public MyContainer
    || Begin meta-data DO NOT EDIT
    format-version = 2,
    design-time-class = "Canvas",
    run-time-class = "Canvas",
    || End meta-data
    width = 315pt,
    height = 250pt,
    background = "#D4D0C8",
    border-width = 1.5pt,
    border-color = "#D4D0C8",
    border-style = "raised",
    font-size = 8pt,
    control-appearance-changeable? = true,

    {layout-element void:MyCommandButton
        || Begin meta-data DO NOT EDIT
        anchor = "top-left",
        x = 45px,
        y = 35px,
        || End meta-data
        {MyCommandButton
        }
    }

    {layout-container void:CommandButton
        || Begin meta-data DO NOT EDIT
        anchor = "top-left",
        x = 180px,
        y = 35px,
        || End meta-data
        {CommandButton
            label = "command-button-1"
        }
    }

    {layout-element void:MyTextField
        || Begin meta-data DO NOT EDIT
        anchor = "top-left",
        x = 45px,
        y = 80px,
        || End meta-data
        {MyTextField
        }
    }

    {layout-element void:TextField
        || Begin meta-data DO NOT EDIT
        anchor = "top-left",
        x = 215px,
        y = 80px,
        || End meta-data
        {TextField
        }
    }

    {constructor public {default}
        {self.initialize-components}
    }
}

MyTextField and MyCommandButton are styled properly after I put them on VLE. But once I close VLE and re-open the layout, my controls lose their styles while normal CommandButton and TextField still have its style.
Please let me know if other lack of information.