A hover script for KSP using RedOnion

hover.lua

window=new(ui.Window,"Hover Dialog",ui.Layout.Vertical)

window.ChildAnchors=ui.Anchors.Fill

hovering = false
target_alt = 0
target_vs = 0
old_throttle = ship.throttle

window.Add(new(ui.Button,"Start Hover",function() 
    print("Start Hover")
    hovering = true
    end))

window.Add(new(ui.Button,"Stop Hover",function() 
    print("Stop Hover")
    hovering = false
    ship.throttle = old_throttle
    autopilot.disable()
    end))

window.Add(new(ui.Label,"Altitude:"))

txtbox = window.Add(new(ui.TextBox,"0"))

window.Add(new(ui.Button,"Update Altitude",function()
    print("Target Altitude: "..txtbox.Text)
    target_alt = tonumber(txtbox.Text)
    end))

window.Add(new(ui.Button,"Higher",function() 
    txtbox.Text = tostring(tonumber(txtbox.Text) + 2)
    target_alt = tonumber(txtbox.Text)
    print("Target Altitude: "..txtbox.Text)
    end))
    
window.Add(new(ui.Button,"Lower",function() 
    txtbox.Text = tostring(tonumber(txtbox.Text) - 2)
    target_alt = tonumber(txtbox.Text)
    print("Target Altitude: "..txtbox.Text)
    end))

while ( true ) 
do
  if ( hovering == true ) then
	  if  (ship.altitude < (target_alt - 2) ) then
		target_vs = 5
		if ( ship.native.verticalSpeed < target_vs ) then
		  ship.throttle = 1
		else
		  ship.throttle = 0
		end
	  elseif ( ship.altitude > (target_alt + 2) ) then
		target_vs = -5
		if ( ship.native.verticalSpeed < target_vs ) then
		  ship.throttle = 1
		else
		  ship.throttle = 0
		end
	  else
		target_vs = 0
		if ( ship.native.verticalSpeed < target_vs ) then
		  ship.throttle = 1
		else
		  ship.throttle = 0
		end
	  end
  end
  
  sleep(0.1)
end