Now that I'm back from vacation, here's more on the solution, as promised. (Divided into two parts, as you can see.)
Again: Don't read it unless you're desperate!
The Brr room seems impossible, doesn't it?
Well, it is. At least if you play by the rules. So here's what you need to do:
Head to the Brr room first. Charge your gloves with all four Brrs - first, you need to get three of the mushroom gates open. Freeze a Spikeyball in the lower left corner so the top-left button will be pressed, and freeze a Spikeyball at the top (don't forget to freeze the water at the top too!) so that the two buttons on the right are pressed. Now that every button is pressed except the one in the lower left corner, you can grab the key and leave the Brr room with one Brr charge left. If you still can't figure out what to do, see the next part.
Throughout the rest of the level, you will go into a room with one charge and leave with another. After leaving the Brr room, use the extra Brr charge to complete the Floing room with an extra Floing charge. Continuing this pattern, the order of the rooms from here on is Blink, Pow, Flash, Grow, Pop, and finally you can use your extra Pop charge to press the button in the Brr room.
I'll update it to fix it so
