Feature request: option for ‘Prompt for User Input’ window to appear under the mouse cursor

From the Wiki:

HTML Window Design

You can define the size and position of the window using any of the following attributes to the HTML body element:

HTML Body Attribute Definition/Use
data-kmwindow May be either: a size (width, height); a rectangle (left, top, width, height)
data-kmwidth width
data-kmheight height
data-kmleft position of left side
data-kmtop position of top
data-kmwindowid an ID that can be used with the Execute a JavaScript in Custom Prompt action

For example:
<body data-kmwindow="SCREEN(Main,Left,20%),SCREEN(Main,Top,20%),420,560">

So how about trying

<body data-kmleft="MOUSEX()" data-kmtop="MOUSEY()">

Add a few pixels to MOUSEY() if you want to account for the title bar and remember that the edge of your screen is a limit -- the window will spawn as close to your pointer as it can while remaining entirely on screen.