Transparent image displayed for flick of a second using Undo action

[grofaty]

Pinta latest development on Ubuntu 12.04.
1. New image: 300 x 300 px.
2. <Print-screen> and paste the image to Pinta using <Ctrl>+V.
3. Dialog appears. Click on "Expand canvas" button.
4. Click on Undo and for a you a flick of a second there is transparent window displayed (= bug) and after that original new image is displayed (this is OK). On slower computer this unneeded "transparent window display" for a flick of a second is more noticeable (on my old computer running Pinta inside virtual machine it is displayed for about half of a second).

This is tiny regression bug appeared after fixing bug 996490 using fix https://github.com/PintaProject/Pinta/commit/9a75ac7d9758127e4d502e9321855ed4ce61f7f8
according to Cam this is due "This is because the new history item is composed of two history items, each of which triggers a re-paint of the canvas." So we have to figure it out how to undo multiple history items without displaying all of the intermediate steps.

P.S. This is not a huge problem, just an annoyance to end-user to display something that is not needed, so you can mark this bug as Low priority.

[grofaty (grofaty)]

Retested using master on Windows XP and this problem does not appear anymore on using Undo, but it does appear using Redo (after Undo was used).