GuiElement interface's mouseClick method returns a boolean which is handled by ComposedElement to prevent mouse clicks on multiple elements at once

ComposedElement's entries are sorted so that GuiDropdown are always drawn on top
Modified thrown UnsupportedOperationExceptions in CustomImageObject to not be thrown if asset is null

src/main/java/eu/crushedpixel/replaymod/assets/CustomImageObject.java

@@ -16,14 +16,10 @@ import java.util.UUID;
 
 public class CustomImageObject implements GuiEntryListEntry {
 
-    public CustomImageObject(String name, UUID assetUUID) {
+    public CustomImageObject(String name, UUID assetUUID) throws IOException {
         this.name = name;
 
-        try {
-            setLinkedAsset(assetUUID);
-        } catch(Exception e) {
-            e.printStackTrace();
-        }
+        setLinkedAsset(assetUUID);
     }
 
     @Getter @Setter private String name;
@@ -43,7 +39,7 @@ public class CustomImageObject implements GuiEntryListEntry {
 
         if(asset instanceof ReplayImageAsset) {
             setImage(((ReplayImageAsset)asset).getObject());
-        } else {
+        } else if(asset != null) {
             throw new UnsupportedOperationException("A CustomImageObject requires a ReplayImageAsset");
         }
     }