When you're posting a dropbox link you need to put your file into the Public folder of your Dropbox folder, and right-click on it and select "Copy public link."
Or if you're using the web interface you click the down-arrow at the end of your file in the Public folder and select "Copy public link." That's the link you post.
The one you posted is the secure link to the file from your web login, we can't download that, so I can't see what's in your .cap.
Anyway, when you use the Attach action for the panel to attach another object, you don't move the panel, it's the other way around. You move the object, and the panel follows it. But you can't add a behavior to SpriteFont, so you can't set it to Drag and Drop.
So if you want to drag and drop a panel and have the text remain inside, you need to use the Attach action in the SpriteFont object. But just setting the position isn't enough, you need to refresh the text inside it:
-> SpriteFont: Attach to Panel
-> SpriteFont: Show text "Hello world!"
Now you can drag the panel around normally and the text will follow. The "Show text" action every tick will update the position of the sprites in the SpriteFont object. Otherwise, it just puts the sprites on the screen in one spot and leaves them there until you do something else with them.
Normally you don't have to use "Show text" every tick, only if you're moving the SpriteFont object around.
Attaching the panel every tick might seem like overkill, but if you don't then the text will lag behind the panel when you drag it. This fixes the issue, the text will remain firmly inside the panel. Normally, if your panel doesn't ever move, you would only need to attach it once.