GestureArea: improve the glowing image

Signed-off-by: Christophe Chapuis <chris.chapuis@gmail.com>
Layout: fix text layout

 * use pixelSize instead of pointSize, because we already take the DPI into accound
 * better layout for the fullLauncher, nicer and more flexible
 * fix the bug where the launchbar disappears when starting an app fails

Signed-off-by: Christophe Chapuis <chris.chapuis@gmail.com>