I am still having the same problem on formpanel validation in mutiple tabs situation.
Each Tabs Item had it's own formpanel and when user click a button, the events basically
get each of the formpanel and called isValid().
As well, The tab panel is using getLayout().setDeferredRender(false).
It looks like the setDefferentRender does not work.
For testing purpose:
* I click button which trigger validation on both formpanel, it does not work.
* I click on other tab item and then click on button which trigger validation on both formpanel, the validation is working.
I would recommend that you perform validation before changing tabs. If the form is valid, you allow to change the tab, otherwise, you stay in the same tab until the form is validated.
I am still having the same issue with form validation, the form is not valid until all tabs with validation perform have been rendered. Do you have any solution to that ?
I have tried tabPanel.setDeferredRender(false) but it doesn't works.