rework splitter implementation

modules/game/gameinterface.otui

@@ -16,6 +16,33 @@ UIWidget
   anchors.fill: parent
   anchors.top: topMenu.bottom
 
+  GameMapPanel
+    id: gameMapPanel
+    anchors.left: gameLeftPanel.right
+    anchors.right: gameRightPanel.left
+    anchors.top: parent.top
+    anchors.bottom: gameBottomPanel.top
+    focusable: false
+
+  UISplitter
+    id: mapSplitter
+    anchors.left: gameLeftPanel.right
+    anchors.right: gameRightPanel.left
+    anchors.bottom: parent.bottom
+    relative-margin: bottom
+    margin-bottom: 172
+    height: 4
+    margin-top: -2
+    background: red
+    @canUpdateMargin: function(self, newMargin) return math.min(math.max(newMargin, 100), self:getParent():getHeight() - 300) end
+
+  GameBottomPanel
+    id: gameBottomPanel
+    anchors.left: gameLeftPanel.right
+    anchors.right: gameRightPanel.left
+    anchors.top: mapSplitter.top
+    anchors.bottom: parent.bottom
+
   GameSidePanel
     id: gameRightPanel
     width: 190
@@ -32,32 +59,6 @@ UIWidget
     anchors.top: parent.top
     anchors.bottom: parent.bottom
 
-  GameBottomPanel
-    id: gameBottomPanel
-    height: 170
-    anchors.left: gameLeftPanel.right
-    anchors.right: gameRightPanel.left
-    anchors.bottom: parent.bottom
-    @onGeometryChange: self:getParent():getChildById('mapSplitter'):setGrow(self:getHeight() > 100)
-
-  GameMapPanel
-    id: gameMapPanel
-    anchors.left: gameLeftPanel.right
-    anchors.right: gameRightPanel.left
-    anchors.top: parent.top
-    anchors.bottom: gameBottomPanel.top
-    focusable: false
-    @onGeometryChange: self:getParent():getChildById('mapSplitter'):setShrink(self:getHeight() > 300)
-
-  UISplitter
-    id: mapSplitter
-    anchors.left: gameBottomPanel.left
-    anchors.right: gameBottomPanel.right
-    anchors.top: gameBottomPanel.top
-    attached-to: gameBottomPanel
-    height: 4
-    margin-top: -2
-
   UIWidget
     id: mouseGrabber
     focusable: false