Hi. Yes you can type CTRL+SHIFT+E to open the files of that skin for editing. Now select the "slide.htt" tab, which is responsible for slide page generation (where the thumbnail strip is. Now edit lines 36 and 38. I changed all references from "7" to "9" in the code snippet below. This generates 9 thumbnails in the strip:
<%-- Thumbnail navigation --%>
<ja:if test="${thumbnailNavigation}">
<%
thisFile = fileName;
thumbstripBefore = 5;
thumbstripBefore = Math.min(thumbstripBefore, imageNum - 1);
thumbstripBefore = Math.max(thumbstripBefore, (imageNum + 9) - (1 + totalImages));
%>
<div id="thumbnav">
<ja:fileiterator start="-${thumbstripBefore}" count="9" exclude="folder, webLocation">