Unity on Ubuntu 17.04

I am running current Ubuntu 17.04 and latest patches apṕlied, running Unity, one screen @ 3200x1800 and start snaptile as user manually.

The most left window is misplaced, the calculation seems to ignore unity launcher, which is on the left (default).
CTRL-ALT-Q-X results in

Absolute upper-left X: 74
Absolute upper-left Y: 65
Relative upper-left X: 0
Relative upper-left Y: 0
Corners: +74+65 -1526+65 -1526-0 +74-0
-geometry 1600x1735+61--13

If I drag the window on the left, so unity changes the size, I get following result:

Absolute upper-left X: 61
Absolute upper-left Y: 65
Relative upper-left X: 0
Relative upper-left Y: 0
Corners: +61+65 -1569+65 -1569-0 +61-0
-geometry 1570x1735+48--13

The report concerns snaptile window placement under Ubuntu 17.04 with Unity and a left launcher; no source files or tests are named. Start by reproducing the two reported geometry outputs and tracing the placement calculation. Done means the leftmost window is positioned without ignoring the launcher, with geometry checked after resizing.

Written by the indexing model from the issue text.