Comment 32 for bug 1547949

I could reproduce the issue every single time in the following way after resetting:
(Resolution:1366X768, dock will be always visible)
Version: elementary OS 0.4 Loki
Mail Version: Mail 1.0.2
System is up-to-date when I'm writing this.

Step 1: Reset mail with dconf reset -f /org/pantheon/mail/

Step 2: Open mail and here is the dump
messages-pane-position=416
folder-list-pane-position-horizontal=149
window-width=1059

Step 3: Maximize mail
window-maximize=true
messages-pane-position=631
folder-list-pane-position-horizontal=149
window-height=690
window-width=1366

Step 4: Decrease the size of message pane position(In other words, increase the second section width by the slider present)more than the size of the resolution
window-maximize=true
messages-pane-position=1078
folder-list-pane-position-horizontal=149
window-height=690
window-width=1571
Now if you notice the width increased more than the resolution.

Step 5: Restore mail
window-maximize=false
messages-pane-position=1065
folder-list-pane-position-horizontal=149
window-height=610
window-width=1707

Step 6: Close and open mail again
Ever increasing!
window-maximize=false
messages-pane-position=1136
folder-list-pane-position-horizontal=149
window-height=610
window-width=1806
(Sometimes, you don't need to do this step, after the step 5, it's ever-increasing)