Add a "set thumbnail" button.

Problem: in various cases, whether it be due to frame size or page size, the thumbnail of a score and the front page of a score are not equal in size. Because of this, it becomes quite awkward to create a thumbnail without ruining the score.

For example, here is what the first page of this example piece of music looks like in the musescore app itself; note that there is no whitespace:

Now, here is what the thumbnail of this example piece of music looks like; I have highlighted the white space:

It should be noted that this is also the thumbnail used on the musescore.com side of things, which makes it look tacky. However, resizing the image to account for this whitespace results in the image going onto the next page in the app itself, which looks even worse, as well as uncentering the text, making it look worse as well.

Proposed solution(s):

1. Add a "set thumbnail" button, either to musescore.com or the application itself, that allows you to set an image as a thumbnail, separate from the first page of the score. This way, we don't have to deal with different page sizes and frame sizes, among other things, and can instead just upload an image and be done.

2. Add a button that adds a special page to the front of your score that specifically functions as a page to place a thumbnail image. It wouldn't be printed out unless you specified to print it and it would simply serve to be a page that is the correct size of an actual musescore thumbnail.

Personally, I prefer solution 1 over 2.