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In ArcMap 10.1, in order to make editing vertices easier transparency was added to the symbols of the feature being edited. This causes a redraw around the feature which is not desirable for complex datasets. The existing behavior is helpful in common cases. So instead of changing it registry key was added to help users who cannot work with the redraw.
Workaround
Add the following registry key for each user: HKEY_CURRENT_USER\Software\ESRI\Desktop10.6\ArcMap\Garcia\editVerticesOpaque
DWORD
0 = Original transparent symbol when editing features.
1 = Sold fill symbol when editing features.
ArcMap 10.6 and ArcMap 10.2.1 with the Utilities and Telecom Update 8 reads the registry key upon startup and changes the behavior accordingly.