Sorry for my delay.
Here comes the fiddle:
https://fiddle.sencha.com/#view/editor&fiddle/1tk3
But I alredy solved this issue.
When I put a combobox as an "editor" of an column, I also set a render for it.
For example:
renderer: function(value, metaData, record, rowIndex, colIndex, store, view) {
var combo = this.columns[colIndex].getEditor();
var combostore = combo.getStore();
var dataIndex = combostore.findExact('id', value);
var recordCombo = combostore.getAt(dataIndex);
return recordCombo.get('name');
},
In this code, I did not check if "value" is null and that is my mistake! This part must to be checked as below:
renderer: function(value, metaData, record, rowIndex, colIndex, store, view) {
if(!value) return '';
var combo = this.columns[colIndex].getEditor();
var combostore = combo.getStore();
var dataIndex = combostore.findExact('id', value);
var recordCombo = combostore.getAt(dataIndex);
return recordCombo.get('name');
},
The solution is quite simple!
Thx!