Redmine

    var mouse_x = Event.pointerX(e);

    var mouse_y = Event.pointerY(e);

    var render_x = mouse_x;

    var render_y = mouse_y;

    var dims;

    var menu_width;

    var menu_height;

    var window_width;

    var window_height;

    var max_width;

    var max_height;

    $('context-menu').style['left'] = (render_x + 'px');

    $('context-menu').style['top'] = (render_y + 'px');		

    Element.update('context-menu', '');

    new Ajax.Updater({success:'context-menu'}, this.url, 

	 dims = $('context-menu').getDimensions();

	 menu_width = dims.width;

	 menu_height = dims.height;

	 max_width = mouse_x + 2*menu_width;

	 max_height = mouse_y + menu_height;

	 var ws = window_size();

	 window_width = ws.width;

	 window_height = ws.height;

	 if (max_width > window_width) {

	   render_x -= menu_width;

	 }

	 if (max_height > window_height) {

	   render_y -= menu_height;

	 }

	 if (render_x <= 0) render_x = 1;

	 if (render_y <= 0) render_y = 1;

	 $('context-menu').style['left'] = (render_x + 'px');

	 $('context-menu').style['top'] = (render_y + 'px');		

// this code can be used for debugging

//	 alert("menu_width=" + menu_width + "\nmenu_height=" + menu_height + "\nmouse_x=" + mouse_x + "\nmouse_y=" + mouse_y +

//	 "\nwindow_width=" + window_width + "\nwindow_height=" + window_height + "\nrender_x=" + render_x + "\nrender_y=" + render_y);

function window_size() {

    var w;

    var h;

    if (window.innerWidth) {

	w = window.innerWidth;

	h = window.innerHeight;

    } else if (document.documentElement) {

	w = document.documentElement.clientWidth;

	h = document.documentElement.clientHeight;

    } else {

	w = document.body.clientWidth;

	h = document.body.clientHeight;

    }

    return {width: w, height: h};

}