Scratchpad:Layer Mechanism

Closed
I tried to adapt the code to play video in the background, but it doesn't work :-(

Why use Layers
Because of we have different plugins which partially use different widgets for displaying content

Description
There will exist some special widgets: 1. "back" for actual theme image 2. "shield" is in front of other widget because it should hide any displayed items without changing the related content 3. "alarm" is in front of all widgets because the alarm should be possible to display in every situation

Now there are two special widgets for handling backgrounds and foreground items The QStackedWidget Object provide the possibility to switch easily between different backgrounds, whereat the other backgrounds will be hided automatically.

Examples are:
 * Phonon widget
 * Future VLC widget
 * maybe a widget for optimized image display

The other QStackedWidget Object manage different foreground widgets, these widgets should be transparent in the most cases.

Examples are:
 * webView widget (this is a special one, because of it can be transparent or not)
 * maybe widgets for displaying flashs, of graphic objects, ...

Advantages

 * Hide and Show mechanism is easier
 * it is not necessary anymore to cache the actual content while hiding (shield) is active
 * provide possiblity for more display widgets (optimized widgets for different content)

Open Issues

 * add mechanism to select the right foreground/background for different plugins

Further Ideas
We should use the same display classes for the preview widgets as for the main Display, because of I have had the effect, that I opened a little movie in the preview -> this works, but after going to live the movie doesn't appeared :-(