[release/9.0] fix #13305 Baseline SnapLines do not appear in DesignSurface #13349
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Backport of #13324 to release/9.0
The cause of this issue
This issue is caused by PR10279
These are two of all changes make in PR10279

BehaviorService
,DragAssistanceManager
useSnapLines
to add some effects during design time.ControlDesigner
has a virtual propertySnapLines
, but most designers override the property, in other words, most designers have customizedSnapLines
Code flow before PR10279
when
BehaviorService
orDragAssistanceManager
accessesSnapLines
, customizedSnapLines
were returned.Code flow after PR10279
ControlDesigner.cs
when
BehaviorService
orDragAssistanceManager
accessesSnapLinesInternal
, customizedSnapLines
were skipped.Proposed changes
SnapLines
Screenshots
Before
After
Test methodology