Using dark theme with white WebView background looks very ugly,
especially when a "download complete message" or a "show images"
button is present.
This change applies the theme to the whole activity.
Also changed the text for the toggle menu. It's also shorter now,
and isn't cut off anymore on hdpi/480px wide devices.
We always allow zooming but hide (provided the Android version supports
it) the on-screen zoom controls if the device supports multi-touch,
hence pinch-to-zoom.
The (undocumented) method WebView.setEmbeddedTitleBar() was removed in
Android 4.1 which caused the message header to never be displayed.
This fallback is only a temporary fix. We really need to come up with a
solution that feels like the previous (setEmbeddedTitleBar) behavior.
The ScrollView around the WebView caused all sorts of problems. This
change removes the ScrollView and uses the undocumented method
WebView.setEmbeddedTitleBar() to set the MessageHeader view as "title
bar" of the WebView. This allows MessageHeader to scroll away making
more room for the WebView.
All of the "magic title bar" code was originally implemented by Jesse
for Kaiten.
Because WebView doesn't support a scrolling footer we can no longer
support scrolling buttons or attachments at the end of the message. Now
users can switch from message view to attachment view via a button just
below the message headers.
I also copied some code for which I was too lazy to create a separate
commit. It allows to display attachments we didn't use to show by
clicking on a "More..." button in the attachment view. Those
attachments are mostly images referenced by the HTML part (e.g.
background images).
Fixes issue 3291
