Stop tooltip disappearing off screen

How can I have my tooltip popup adjust its position if it’s drawning off screen?

Coding in C#.

if (hoveringOverPlace == true)
{
//Vector3 pos = hoveringPlace.transform.position;

			Rect windowRect = new Rect(Input.mousePosition.x+20, 
		                           Screen.height-Input.mousePosition.y - 60, (Screen.width / 2) - 500, (Screen.height / 2) - 300);
		
			windowRect = GUI.Window(0, windowRect, PlaceInfo, hoveringPlace.name); 
		}
	}

	void PlaceInfo(int windowID) {

		GUI.Label(new Rect(10, 20, (Screen.width / 2) - 500, (Screen.height / 2) - 300), wrapString(labelText, 300));
	}

Try this works only if tooltip disappears offscreen in horizontal outside screen is a bool

if (Input.mousePosition.x < Screen.width && Input.mousePosition.x > 0) {
				windowRect = new Rect (Input.mousePosition.x, 
				                       Screen.height - Input.mousePosition.y - 60, (Screen.width / 2) - 500, (Screen.height / 2) - 300);
				outsideScreen = false;
			}
			else if(Input.mousePosition.x >= Screen.width && !outsideScreen)
				{
				windowRect = new Rect(windowRect.x, 
					                           Screen.height-Input.mousePosition.y - 60, (Screen.width / 2) - 500, (Screen.height / 2) - 300);
				outsideScreen = true;
				
				}
			else if(Input.mousePosition.x <= 0 && !outsideScreen)
			{
				windowRect = new Rect(windowRect.x - (windowRect.width), 
				                      Screen.height-Input.mousePosition.y - 60, (Screen.width / 2) - 500, (Screen.height / 2) - 300);
				outsideScreen = true;
			}
			windowRect = GUI.Window (0, windowRect, PlaceInfo, "ToolTip"); 
		}