function calcAvailableHeight() {
        var availableHt = $windowContent.height();

        $editorHolder.siblings().each(function (i, elem) {
            var $elem = $(elem);
            if ($elem.css("display") !== "none" && $elem.css("position") !== "absolute") {
                availableHt -= $elem.outerHeight();
            }
        });

        // Clip value to 0 (it could be negative if a panel wants more space than we have)
        return Math.max(availableHt, 0);
    }
Calculates the available height for the full-size Editor (or the no-editor placeholder),
accounting for the current size of all visible panels, toolbar, & status bar.
@return {number}