When placing base facilities larger than 1x1 squares (which is basically just the hangar as-is), the facility outline indication under the cursor disappears when the cursor hovers above the bottom row and the rightmost column. When clicking LMB to place the facility the error dialog that appears is related to non-connectedness with other facilities rather than its "out of base bounds" placement.
Making special cases for outline placement in relation to cursor position when over bottom row and rightmost column could solve the problem. By default the cursor is in the top-left square of the facility placement outline. When the cursor hovers over the bottom row it could be in the bottom-left square. When the cursor hovers over the rightmost column it could be in the top-right square. And when the cursor hovers over the bottom row *and* the rightmost column (the bottom-right square of the base grid) it could be in the bottom-right square.
Such a change would also be useful if anybody decided to implement strange and wonderful new facility types larger than 1x1 square sometime in the future!
From talking to SupSuper I realize that he actually implemented facility placement to original spec - I forgot to have a look at UFO:EU before I reported it as a bug. It seems the original implementation continues to baffle with its bad usability.
