added a "use custom url" button

src/core/Global.ttslua

@@ -691,6 +691,13 @@ function onClick_select(_, _, identificationKey)
   updatePreviewWindow()
 end
 
+-- click function for the "Custom URL" button in the playarea image gallery
+function onClick_customUrl(player)
+  player.showInputDialog("Enter a custom URL for the playarea image", "", function(newURL)
+    playAreaApi.updateSurface(newURL)
+  end)
+end
+
 -- click function for the download button in the preview window
 function onClick_download(player)
   local params = library[contentToShow][currentListItem]

xml/Global/PlayareaGallery.xml

@@ -12,6 +12,13 @@
   <Button class="bWhite"
     color="white"/>
 
+  <Button class="windowButton"
+    hoverClass="bGrey"
+    pressClass="bWhite"
+    selectClass="bWhite"
+    color="#888888"
+    font="font_teutonic-arkham"/>
+
   <!-- image boxes in the grid -->
   <VerticalLayout class="imageBox"
     color="black"
@@ -58,6 +65,12 @@
       font="font_teutonic-arkham"
       preferredWidth="600"
       alignment="MiddleLeft">Playarea Image Gallery</Text>
+    <Button id="customUrl_button"
+      class="windowButton"
+      onClick="onClick_customUrl"
+      height="30"
+      preferredWidth="125"
+      fontSize="24">Use custom URL</Button>
     <Panel preferredWidth="50">
       <Button rectAlignment="MiddleRight"
         width="50"