Dialog Button placement should be consistent.

[scythetwirler]

The Yes/No, Continue/Cancel button placement on dialogs is inconsistent.

[scythetwirler]

The team has agreed to adhere to the Windows button placements standards (​http://wildfiregames.com/meetinglogs/0ad-staff.2014-10-19-18.05.html)

[historic_bruno]

Since nobody has worked on this and it has been a problem for years, I decided to clean up the button order. Unfortunately, using the Windows order would require switching the buttons for almost every dialog in the game. That's a disruptive experience for all the users, while only the following less-frequently used dialogs are inconsistent (that I know about):

• Resign confirmation
• In-game manual
• Splashcreen

So I am only going to change the order for those, and fix the Esc behavior (#3200) for all of them.

[ben]

In 16736:

Fixes button order consistency in a few places: resign confirmation, manual, splashscreen, fixes #2837. NOTE: the convention is Cancel/Back button on the left, other action buttons are to the right. Please report any you find that don't match that!
Adds hotkey.cancel mapped to the Escape key, which is now used for closing/canceling in-game dialogs, fixes #2636, #3200. Please report any dialogs where Esc doesn't work!