Check out the patch notes for the v19 Winter Mischief update here:

Collapse Furniture Window UI in House Edit Mode

MapleStory 2 Rep: 520
Posts: 7
in Suggestions and Feedback
When I'm editing my house, and I'm only using one block, and I just want to be able to see what I'm working on, it is very obnoxious to have this large white furniture window taking up almost a sixth of my screen. All of the other house-related UI elements are collapsible, except for this one. Collapsing the furniture window would make creating houses much more enjoyable.