The various dialogs above the minimap all dismiss when you press either "Close window" (default bound to Q I think?) or "Toggle menu" (default bound to ESCAPE). However, the Blueprint Library only dismisses with "Toggle menu", not "Close window." The same is true of subwindows inside the library, like when you right-click on a blueprint.
Interestingly, the same is *not* true of right-clicking on blueprints in your inventory - they dismiss with "close window" as expected.
[Oxyd] [0.15.28] Blueprint dialog doesn't dismiss with close window
Re: [Oxyd] [0.15.28] Blueprint dialog doesn't dismiss with close window
Thanks. This will be fixed in 0.15.29.