These options have been removed:
```
timeline_opacity
timeline_chapters_opacity
volume_opacity
speed_opacity
menu_opacity
menu_parent_opacity
top_bar_title_opacity
window_border_opacity
curtain_opacity
```
and replaced with one comma delimited `opacity` list to override all of the above and some new default opacity values.
Example:
```
opacity=timeline=0.5,title=0.5
```
List of opacity values available for override and their current defaults:
```
timeline=.9
position=1 # timeline progress or line
chapters=0.8
slider=0.9 # background of all sliders, such as volume
slider_gauge=1 # value bar of all sliders
speed=0.6
menu=1
submenu=0.4
border=1 # window border
title=1 # window title
tooltip=1 # tooltip background
thumbnail=1 # thumbnail border
curtain=0.5
```
closes#584, closes#636, closes#675