Solution won't compile using Visual Studio 2017

[obrienj970]

When I try to compile the solution the error list is as follow:

Severity Code Description Project File Line Suppression State
Error CS0535 'AreaHandler' does not implement interface member 'IAreaHandler.MouseCrossed(AreaBase, bool)' Histogram C:\DFNetResearch-Projects-Core\Source\DevZH.UI-master\samples\Histogram\AreaHandler.cs 11 Active
Error CS0535 'Page15.AreaHandler' does not implement interface member 'IAreaHandler.MouseCrossed(AreaBase, bool)' Tester C:\DFNetResearch-Projects-Core\Source\DevZH.UI-master\samples\Tester\Page15.cs 128 Active
Error CS0535 'Page6.AreaHandler' does not implement interface member 'IAreaHandler.MouseCrossed(AreaBase, bool)' Tester C:\DFNetResearch-Projects-Core\Source\DevZH.UI-master\samples\Tester\Page6.cs 13 Active
Warning CS0168 The variable 'ex' is declared but never used DevZH.UI C:\DFNetResearch-Projects-Core\Source\DevZH.UI-master\src\DevZH.UI\Application.cs 114 Active