Clarify update prompt wording and interaction

[Pidgeot]

Several people have reported concern due to the wording in the update prompt - specifically that clicking 'update' will automatically download the new version and may overwrite user data. Changing the text of the prompt from Update now? to Download now? would clarify this.

The relative placement of the check again options and yes/no buttons can also be confusing, as it seems to be confirming the time to check again.

Unlike the other dialogue boxes (eg for graphics install), the update prompt always appears in the top-left of my screen rather than in the centre.

I propose a couple of interface enhancements:

• The update prompt should be centred, like the others

• If an update is available, show a dialogue box with text 'An update is available (version $ver_str)' and two buttons, Download and Not now - avoiding use of the more general verb 'update'.

• If Download is clicked, open the page (nb - could direct download as an extra enhancement later)

• If Not now is clicked, then a new dialogue box opens and prompts the user to choose when next to be reminded. A dropdown menu would be a poor choice here as space is not limited and visibility would be good - I would suggest a set of exclusive checkboxes and either go with the first clicked or have an OK button at the bottom.

[Issue created by PeridexisErrant: 2014-09-23]

[Comment created by Pidgeot: 2014-09-23]
Improve update dialog (fixes #30)

→ <<cset 2f115969cf04>>

[Comment created by PeridexisErrant: 2014-09-23]
Yep, that sounds better than a second dialogue window. The other parts stand though..

[Comment created by Pidgeot: 2014-09-23]
Technically, we don't really need the dropdown anymore; it's a menu item now. Perhaps it would be simpler to just replace it with a note saying how to change it? Something like:

You can control the frequency of update checks from the File > Check for Updates menu.