Ensure that dialogs can be scrolled vertically.

client/atompm.html

@@ -147,7 +147,9 @@
 		
 
 		<div id="div_dim_bg" class="dim_bg" style="display:none"></div>
-		<div id="div_dialog" class="dialog" style="display:none;text-align:center"></div>		
+		<div id="centerpoint" class="center_point">
+		    <div id="div_dialog" class="dialog" style="display:none;text-align:center"></div>
+        </div>
 		<div id="div_geom_ctrls" class="geometry_ctrls" style="display:none"></div>
 	</body>
 </html>

client/styles.css

@@ -161,12 +161,18 @@ html {
     margin: 0;
 }
 
+.center_point {
+    top: 50%;
+    left: 50%;
+    position: absolute;
+}
 
 .dialog {
-    position:absolute;
+    position:relative;
+    min-height: auto;
+    max-height: 80%;
+    width: 50%;
     padding:0 20px 20px;
-    max-height:100%;
-    max-width:100%;
     z-index: 30;
     background-color: whitesmoke;
     border:2px solid crimson;