Working on CommonUI conversion. Need to stop using SetAnchorsInViewport as way to position widgets, so now implementing new thing using GridPanels.

Source/Integration/UtilityLibrary.h

@@ -85,4 +85,51 @@ public:
 			FVector2D PixelXY, double MaxDistanceFromCamera,
 			ETraceTypeQuery TraceChannel, bool bTraceComplex, EDrawDebugTrace::Type DrawDebugType, bool bIgnorePlayerPawn,
 			const TArray<AActor*>& ActorsToIgnore, FHitResult& HitResult);
+
+	// Set Position of GridPanel Middle Cell
+	//
+	// Sometimes, you want to specify the position of a widget, and you
+	// don't want to specify the position in slate units, instead, you
+	// want to specify the position using fractions: ie, (0,0) is the
+	// upper left corner of the screen, and (1,1) is the lower-right corner.
+	//
+	// One way to accomplish this is to put your widget in the middle cell
+	// of a 3x3 GridPanel.  Then, you can position it by adjusting the grid
+	// fill rules.  This utility routine can do the math necessary to
+	// correctly populate those fill rules.
+	//
+	// This routine must be passed a 3x3 GridPanel.  This will reposition
+	// the middle cell.  You must specify the upper-left and lower-right
+	// corners of the middle cell as fractions between (0,0) and (1,1).
+	//
+	// Be aware that if the content of a grid cell overflows the amount of
+	// space allocated for it, then the grid will adjust to make room.
+	// But that will mean that the grid is no longer faithful to the 
+	// positions specified in its fill rules.  One way to ensure that the
+	// grid remains faithful to its fill rules is to put an Overlay
+	// into the GridPanel cell, then put -1000 padding into the
+	// Overlay's GridPanel slot, then put +1000 padding into the Overlay
+	// slot.  The two paddings cancel each other out, leaving the item in
+	// the Overlay at the originally-intended position.  But if the item
+	// in the overlay overflows, it doesn't cause the Grid to deform.
+	// Instead, the item exceeds the bounds of the grid cell, but it leaves
+	// the grid cell where it belongs.
+	// 
+	UFUNCTION(BlueprintCallable, Category="Widget")
+	static void SetPositionOfGridPanelMiddleCell(UGridPanel *GridPanel, FVector2D UpperLeftXY, FVector2D LowerRightXY);
+
+	// Get Position of GridPanel Middle Cell
+	//
+	// The routine must be passed a 3x3 GridPanel.  This will return the
+	// position of the middle cell of the gridpanel, expressed on a scale
+	// from (0,0) to (1,1).
+	// 
+	// The numbers returned by this routine are based entirely on the
+	// GridPanel fill rules.  If an item in the grid is overflowing its
+	// allocated space, causing the grid to deform, then that won't be
+	// reflected in the output of this routine.
+	//
+	UFUNCTION(BlueprintPure, Category="Widget")
+	static void GetPositionOfGridPanelMiddleCell(UGridPanel *GridPanel, FVector2D &UpperLeftXY, FVector2D &LowerRightXY);
+
 };