Update alert.lua: allow window object as parameter (#3542)

allow also a `hs.window` object as an parameter

Author: muescha

extensions/alert/alert.lua

@@ -100,7 +100,7 @@ local showAlert = function(message, image, style, screenObj, duration)
 --        print(finspect(message:asTable()))
     end
 
-    local screenFrame = screenObj:fullFrame()
+    local screenFrame = screenObj.fullFrame and screenObj:fullFrame() or screenObj:frame()
 
     local absoluteTop = screenFrame.y + (screenFrame.h * (1 - 1 / 1.55) + 55) -- mimic module behavior for inverted rect
     if thisAlertStyle.atScreenEdge > 0 then
@@ -225,7 +225,7 @@ end
 ---  * str     - The string or `hs.styledtext` object to display in the alert
 ---  * image   - The image to display in the alert
 ---  * style   - an optional table containing one or more of the keys specified in [hs.alert.defaultStyle](#defaultStyle).  If `str` is already an `hs.styledtext` object, this argument is ignored.
----  * screen  - an optional `hs.screen` userdata object specifying the screen (monitor) to display the alert on.  Defaults to `hs.screen.mainScreen()` which corresponds to the screen with the currently focused window.
+---  * screen  - an optional `hs.screen` or `hs.window` userdata object specifying the screen (monitor) or window to display the alert on.  Defaults to `hs.screen.mainScreen()` which corresponds to the screen with the currently focused window.
 ---  * seconds - The number of seconds to display the alert. Defaults to 2.  If seconds is specified and is not a number, displays the alert indefinitely.
 ---
 --- Returns: