The Boost theme removed the two upper-right icons in blocks that provided the ability to "collapse" and "dock" side blocks. In
MDL-56018, a request to add "docking" was alleviated because of "something new," probably the newer side bar. I can understand this.
However, I believe that there is still a need to be able to collapse the blocks, meaning that the little "minus" icon should be retained. I believe this because some blocks can get pretty long, and some blocks might not be useful to students, so I desire that students should be able to collapse these blocks.
For example, I use the RSS feed blocks to provide easy access to my lecture videos (using podcast technology.) At the end of my semester, this list grows pretty long (see attached graphic.) Additionally, I like to also use a redundant RSS feed block for open-captioned versions of my videos, again long. I like to tell students that they can collapse the block that is of no interest to them.
As another example, I provide both the Calendar block and the Upcoming Events block. I like the ability for students to collapse either of these if they happen to prefer one over the other.
So I request that the "minus" icon be retained on blocks in the Boost theme. I think that this becomes even more important with Boost since we now have only one side column for blocks. (Incidentally, I really am eager to switch from MORE to Boost, but this inability to collapse blocks might be a show-stopper.)