Question

1. My panel with border layout looks like this:

   var oSplitPanel = Ext.create('Ext.panel.Panel', {
    lid   : 'splitpanel',
    layout: 'border',
    border: 0,
    style: { border: 0 }
    height: 150,
    items: [{
      split: true,
      flex: 1,
      region: 'west',
      xtype: 'panel',
      lid: 'panelwest',
      layout: 'fit',
      minWidth: 200
    }]
   });
   

2. Then another panel gets added to this west region panel:

   oSplitPanel.query('[lid=panelwest]')[0].add(oExplorerPanel);
   

3. Then this split panel gets added to my main view:

   that.getView().add(oSplitPanel);
   

4. Then in another function, I add the center panel:

   var oAddPanelRight = {
          split: true,
          flex: 3,
          region: 'center',
          xtype: 'panel',
          lid: 'panelcenter',
          layout: 'fit',
          border: 0
       };
   
   oSplitPanel.add(oAddPanelRight);
   

Problem:

Everything works perfect this way, however I want to change (limit) the splitter’s own width (this splitter is in between west and center panels to resize their width).

What I tried:

1. Try to change the width of splitters:

    listeners: {
       afterrender: function() {
          // error following, 'splitters' does not exist
          oSplitPanel.layout.splitters.west.setWidth(1);
          oSplitPanel.doLayout();
       }
    }
   

2. Adding a negative margin to the center panel:

            // Tried this:
            margin: '0 0 0 -4'
   
            // And that:
            style: {
               border: 0,
               marginLeft: '-3px'
            }
   

Answer 1

Your oSplitPanel object/instance does not have the split param set to true and has therefor no splitter applied. The splitter get applied to oAddPanelRight object/instance and the nested panel of the oSplitPanel, maybe also to the panel you add later. Can’t tell that.

So you just looked at the wrong class.

Btw. to get a splitter for the class itself you don’t need look at oSplitPanel.layout.splitters Just look at the splitter prop of the class.