`ScrollableView`: merge (some) changes from eXept ...to make it work with recent UI builder.

Only set `Dialog` global to `DialogBox` if not already set This allows other packages to set custom `Dialog` objects.

cherry-picked GenericToolbarIconLibrary.st from 020158c929bb: * 4ecbe3a93aec: Merge, HG Automerge * 8e9dcb2a6533: #REFACTORING by cg, Claus Gittinger <cg@exept.de> * 58d88b144b2b: Merge, HG Automerge * 33c75b4a9999: #REFACTORING by mawalch, mawalch * 74f6a697ee26: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 7b8ba07cb680: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 0122e4e6c587: #FEATURE by cg, Claus Gittinger <cg@exept.de> * e296fa4b5ccb: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 6db292aae07d: #OTHER by mawalch, mawalch * 4366b65a2c8a: Copyright updates, Jan Vrany <jan.vrany@fit.cvut.cz> * 6b79d8bfdcd9: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 6a0103018ab9: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 87fbb0b00ca6: #REFACTORING by cg, Claus Gittinger <cg@exept.de> * 5c977f62957a: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 0ccfd6c3c75f: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 3926b9ae0a3c: #BUGFIX by cg, Claus Gittinger <cg@exept.de> * 8cebd063aeb5: #REFACTORING by cg, Claus Gittinger <cg@exept.de> * 5445f50f8b2b: #REFACTORING by cg, Claus Gittinger <cg@exept.de> * 272618940466: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 56bd6e2384a4: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * ffa93f79e6ae: #DOCUMENTATION by cg, Claus Gittinger <cg@exept.de> * 9410312a11cb: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 0036104e42ed: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 21fad03d5f11: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 8fd99a9d1d84: #REFACTORING by cg, Claus Gittinger <cg@exept.de> * e4ed7fc09ca1: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 2c79a677e38a: #BUGFIX by cg, Claus Gittinger <cg@exept.de> * 81227f5c6bfa: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * a7d893a3c1e1: #FEATURE by cg, Claus Gittinger <cg@exept.de> * 7928d87ff963: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 6ed15ff79b07: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * a1a9e33d6daf: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 07f0100f7064: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * 23d027d53e04: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 823ff944a2a5: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 046733c3db59: #REFACTORING by exept, Claus Gittinger <cg@exept.de> * 040921add07a: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * 5777bb6431cb: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * 27448b51c873: #FEATURE by exept, Claus Gittinger <cg@exept.de> * 1309dd75d7f5: #FEATURE by exept, Claus Gittinger <cg@exept.de> * 6415731ee5e5: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * c7802dbb6d7d: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * 23bf1e00dc95: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 645f74e46f86: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 236c24a6ce6c: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 8db4c188c57a: #REFACTORING by exept, Claus Gittinger <cg@exept.de> * 5d1367f2f32a: #BUGFIX by exept, Claus Gittinger <cg@exept.de> * e012b62927a6: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * cec8de8d957c: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 8e9b8e68a545: #FEATURE by cg, Claus Gittinger <cg@exept.de> * 5274979b30fb: #FEATURE by cg, Claus Gittinger <cg@exept.de> * 73e483e60e05: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * dc6e33c97410: #UI_ENHANCEMENT by cg, Claus Gittinger <cg@exept.de> * 041ace9885e8: #TUNING by cg, Claus Gittinger <cg@exept.de> * bdfd1b407c29: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * 52afc5fcc948: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * f9c23ed981dc: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * 2678c19d0794: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * 043c6c163b4f: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * 5e779e09b004: version method, Claus Gittinger <cg@exept.de> * 51394e1ee44c: #FEATURE by exept, Claus Gittinger <cg@exept.de> * c6a190f66fb7: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * 34b9831cd1ee: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * 3fa783b7f48d: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * b46f5a561997: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * 3bedf44e10d1: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * d0ccad2a39b8: #FEATURE by exept, Claus Gittinger <cg@exept.de> * 20f0d7ec75e0: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * 86c9b274be4e: #FEATURE by stefan, Stefan Vogel <sv@exept.de> * 4c58992375bb: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * 4facc54a9585: #OTHER by exept, Claus Gittinger <cg@exept.de> * d9b1c96aa2b8: #REFACTORING by exept, Claus Gittinger <cg@exept.de> * de0b89624b00: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * 8d5a93082103: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de> * c06c9bee59db: #UI_ENHANCEMENT by exept, Claus Gittinger <cg@exept.de>

Testing FontPanel initialization with incomplete Font information

Fixing a crash when font face and style were nil when selecting font This usually happens with the default settings.stx file.

`CodeViewTheme`: more suitable defaults for unimplemented selector

Theming: add support for theming navigation service's styles ...such as background for selected variable, selector or assignment.

Add AdwaitaDarkToolbarIconLibrary

`Scroller`: fix drawing of scoller background

`ScrollableView`: respect scrolled view's border width ...if no explicit border is set for scrollable views.