Fixed logical tree, added ContentPropertyAttribute
Merge pull request #1123 from 100GPing100/patch-5

BaseMetroDialog - Fixed LogicalTree, Added ContentPropertyAttribute
Fixes #1067
Fixed color issue on all accents except Blue as it was not broke.
Added new Accent named Taupe.
Added GroupBox to Accent Flyout on FlyoutDemo to demonstrate the fixed colors.
Merge pull request #1126 from Tide/1067-tide-accent-color-fix

Fixes #1067