Merge pull request #1846 from skendrot/GridSplitterMinWidth

Fix GridSplitter violating min width of columns

Author: michael-hawker

Microsoft.Toolkit.Uwp.UI.Controls/GridSplitter/GridSplitter.Events.cs

@@ -194,6 +194,11 @@ private bool VerticalMove(double verticalChange)
             // if sibling row has fixed width then resize it
             else if (!IsStarRow(SiblingRow))
             {
+                // Would adding to this column make the current column violate the MinWidth?
+                if (IsValidRowHeight(CurrentRow, verticalChange) == false)
+                {
+                    return false;
+                }
                 if (!SetRowHeight(SiblingRow, verticalChange * -1, GridUnitType.Pixel))
                 {
                     return true;
@@ -254,6 +259,12 @@ private bool HorizontalMove(double horizontalChange)
             // if sibling column has fixed width then resize it
             else if (!IsStarColumn(SiblingColumn))
             {
+                // Would adding to this column make the current column violate the MinWidth?
+                if (IsValidColumnWidth(CurrentColumn, horizontalChange) == false)
+                {
+                    return false;
+                }
+
                 if (!SetColumnWidth(SiblingColumn, horizontalChange * -1, GridUnitType.Pixel))
                 {
                     return true;