1327017 - Several redraw issues in memory tool after switching toolbox mode (nomal/WindowHost)

Status: NEW

(DevTools :: Memory, defect, P3)

Description

[arni2033]

>>>   My Info:   Win7_64, Nightly 49, 32bit, ID 20160526082509
STR_1:
1. Open https://www.mozilla.org/en-US/firefox/nightly/firstrun/
2. Open devtools -> memory, take snapshot
3. Switch toolbox mode (nomal/WindowHost)
4. Hover mouse over the center of the snapshot, hold left mouse button, move mouse to the top-left
   corner of the screen, then to top-right corner, bottom-right corner, bottom-left corner.

AR: 
 There's some graphic corruption in snapshot: there's "real" rectangle with the data, and there's
 "fake" rectangle with the same data drawn below the 1st one. Both cause some redraw issues in Step 4
ER:
 No glitches.
 
Note:
 Assuming this is a mistake in handling <canvas> element, this is not graphics bug.
 _Probably_ it's a general problem with handling <canvas> in devtools, when you look at bug 1240176.