fix locked taskbar autohide in Windows

tooltip.ps1

# sometimes the autohide of the Windows taskbar doesn't work anymore
# and the taskbar is showed permanently
#
# beside killing and restarting the explorer.exe process it's enough
# forcing to display a new tooltip
[reflection.assembly]::loadwithpartialname("System.Windows.Forms")
[reflection.assembly]::loadwithpartialname("System.Drawing")
$notify = new-object system.windows.forms.notifyicon
$notify.icon = [System.Drawing.SystemIcons]::Information
$notify.icon = [System.Drawing.SystemIcons]::Error
$notify.visible = $true
$notify.showballoontip(10,"fix balloontip hiccup ","auto hide should work again",[system.windows.forms.tooltipicon]::None)