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SamBent commentedDec 2, 2019
Ask Mode Template:
Description
After every layout pass, a SharedSizeGroup re-evaluates its shared size and updates the state of its constituent ColumnDefinitions. The goal is to mark the "long-pole" definitions (the largest ones in the group), and to identify Grids that need to be remeasured. The logic for this is flawed in several ways; both goals can fail in either direction (false positive or false negative). These flaws usually result in redundant layout work - the Grids get measured twice, with the mistakes in the second pass cancelling those in in the first - but correct layout results. But in some cases they lead to an infinite cycle of re-layout; the app hangs. In the customer's scenario this happens when
a. the Grids are within the scope of a ScrollViewer with VerticalScrollbarVisibility="Auto"
b. there are more than 157 Grids (the threshold for coalescing pending measure tasks into one task at the root)
c. the minimum width of a non-long-pole Grid increases, away from the shared column
Customer Impact
Hang.
Regression
No. (Port of servicing fix for .NET 4.5.2 - 4.8)
Risk
Low
Fixes #2222
Hang during layout when using SharedSizeGroup