CSSTUDIO-3524 Fix equal spacing of widgets in Display Builder

app/display/editor/src/main/java/org/csstudio/display/builder/editor/actions/ActionDescription.java

@@ -620,7 +620,7 @@ public void run(final DisplayEditor editor, final boolean selected)
                                            .mapToInt(w -> w.propHeight().getValue())
                                            .sum();
 
-            final int offset = ( max - min - totalHeight ) / ( N - 1 );
+            final double offset = ( (double) max - (double) min - (double) totalHeight ) / ( (double) N - 1.0 );
             final List<Widget> sortedWidgets = widgets.stream()
                                                       .sorted(( w1, w2 ) ->
             {
@@ -680,14 +680,14 @@ else if ( w1y >= w2y && w1y + w1h >= w2y + w2h )
                 //  Equal gap distribution...
                 //  ------------------------------------------------------------
                 Widget widget = sortedWidgets.get(0);
-                int location = widget.propY().getValue();
+                double location = widget.propY().getValue();
                 int height = widget.propHeight().getValue();
 
                 for ( int i = 1; i < N - 1; i++ )
                 {
                     widget = sortedWidgets.get(i);
                     location += height + offset;
-                    undo.execute(new SetWidgetPropertyAction<>(widget.propY(), location));
+                    undo.execute(new SetWidgetPropertyAction<>(widget.propY(), (int) Math.round(location)));
                     height = widget.propHeight().getValue();
                 }
             }
@@ -703,19 +703,19 @@ else if ( offset < 0 )
                 int location = widget.propY().getValue();
                 int height = widget.propHeight().getValue();
 
-                final int bottomCenter = location + height / 2;
+                final double bottomCenter = (double) location + (double) height / 2.0;
 
                 widget = sortedWidgets.get(0);
                 location = widget.propY().getValue();
                 height = widget.propHeight().getValue();
 
-                final int topCenter = location + height / 2;
-                final int coffset = ( bottomCenter - topCenter ) /  ( N - 1 );
+                final double topCenter = (double) location + (double) height / 2.0;
+                final double coffset = ( bottomCenter - topCenter ) /  ( (double) N - 1.0 );
                 for ( int i = 1; i < N - 1; i++ )
                 {
                     widget = sortedWidgets.get(i);
                     height = widget.propHeight().getValue();
-                    undo.execute(new SetWidgetPropertyAction<>(widget.propY(), ( topCenter + i * coffset ) - height / 2));
+                    undo.execute(new SetWidgetPropertyAction<>(widget.propY(), (int) Math.round(( topCenter + (double) i * coffset ) - (double) height / 2.0)));
                 }
             }
         }