[GB.DRAW]
* NEW: Support for 'Style.Default' constant.
[GB.GTK]
* NEW: Style: Add 'Default' constant. It tells the Style routine to use the current painted control (if it exists) as a context.
[GB.GTK3]
* NEW: Style: Add 'Default' constant. It tells the Style routine to use the current painted control (if it exists) as a context.
* BUG: Style: Painting the backgroud correctly takes the background color into account, unless for active state (i.e. pressed buttons).
[GB.QT4]
* NEW: Style: Add 'Default' constant. It tells the Style routine to use the current painted control (if it exists) as a context.
* NEW: 'Style.StateOf()' always adds the 'Style.Default' constant.
[GB.QT5]
* NEW: Style: Add 'Default' constant. It tells the Style routine to use the current painted control (if it exists) as a context.
* NEW: 'Style.StateOf()' always adds the 'Style.Default' constant.