1.1.2575 rev1172 Linux, no mods.
Assume XY coordinates with origin at the middle of screen.
Open Architect menu.
Move mouse cursor to upper right quadrant of screen and let go of the mouse.
Push any hotkey for mining, roof area, construct furniture or such.
The small icon that follows the mouse cursor will appear in inverted Y position, instead of right next to the mouse cursor.
Move mouse.
The icon follows the mouse cursor properly.
Push and hold shift key. (Most keys actually work for this.)
Move mouse.
The icon follows the mouse cursor properly.
Release shift key.
The icon again snaps to inverted Y position.
Tapping shift, move the mouse cursor to the upper right quadrant so that the misplaced icon appears on top of the game date and season area. Don't move the mouse and move the camera with wasd or the arrow keys.
A tooltip will pop open, describing the game date and season.
The tooltips will also pop open without any tool selected if you happen to have mouse cursor in a "correct" position, and use the keyboard. Typically this happens, if you use the keyboard to scroll around the map.
This has existed since 0.18.1722 rev1251. Versions 0.17.1557 rev1148 and earlier don't exhibit the same behavior.