Percent is the degree of opacity. 100 is normal. Zero is completely transparent.

This command does not work on child windows. Therefore it doesn't work on buttons that are part of a panel. You can make such buttons invisible with HideWin.

This command does not work on all windows but it does work on HotkeyNet's panels.

This command affects the window that was previously targeted with TargetWin, SendWin, etc.

You can use SetPanelStyle to make a panel's background invisible so only the buttons can be seen and clicked.

This command is implemented with the operating system's WS_EX_LAYERED style.

This hotkey toggles a panel from normal to 50% transparent and back.

<Hotkey F1>
   <Toggle>
      <TargetWin MyPanel>
      <SetWinOpacity 50>
   <Toggle>
      <TargetWin MyPanel>
      <SetWinOpacity 100>