p:selectOneButton suddenly stops working, first button is not clickable anymore - jsf

Question

I have been successfully been using the PrimeFaces selectOneButton - using PF 3.5.
Suddenly, it has stopped working, and the first button is always not clickable - there has been no changes to the webpage code nor the backing bean code (which would affect it).
<p:selectOneButton value="#{bean.result}">
<f:selectItems value="#{bean.options}" />
<p:ajax event="change" process="popupPanel"
update="Grid"
listener="#{myBackingBean.submitItem(bean.itemId)}" />
</p:selectOneButton>
I have a theory to why the first button is not clickable.
From PrimeFaces SelectOneButton showcase:
SelectOneButton is an input component to select options using regular buttons instead of radio buttons
So, SelectOneButton is really radio buttons, but displayed with a nice touch ;)
Now, the rendered HTML of selectOneButton with two options is as follows;
<div class="ui-button ui-widget ui-state-default ui-button-text-only ui-corner-left ui-state-active">
<input id="mainForm:Grid:0:j_idt64:0" name="mainForm:Grid:0:j_idt64" type="radio" value="Yes" class="ui-helper-hidden" checked="checked">
<span class="ui-button-text ui-c">Yes</span>
</div>
<div class="ui-button ui-widget ui-state-default ui-button-text-only ui-corner-right">
<input id="mainForm:Grid:0:j_idt64:1" name="mainForm:Grid:0:j_idt64" type="radio" value="No" class="ui-helper-hidden">
<span class="ui-button-text ui-c">No</span>
</div>
I notice two differences...
1) The div classes are different.
2) First option has checked="checked"
1) Checking the CSS of the div class, I cannot see anything major to which would make the button unclickable.
2) Obviously, since its really a radio button, the first option is "checked".
Now, when clicking a plain-old-standard radio button, you can't click on it to "release it" - once its clicked its clicked, and other radio buttons need to be clicked to change the option.
Since my first option is always "checked" would this block the button to be "clickable"? Has any one else ever experienced something similar? Having looked around I seem to be the only one who has had this issue.
I can do workarounds, but I can not find out why it has suddenly stopped working, and would rather find a solution!
Any help is appreciated!
UPDATE
Luckily, I found an old previous version of my webapp and I checked the rendered HTML.
Heres the following HTML of the first button (which is unclickable on my current version).
<div class="ui-button ui-widget ui-state-default ui-button-text-only ui-corner-left">
<input id="mainForm:Grid:0:j_idt63:0" name="mainForm:Grid:0:j_idt63" type="radio" value="Yes" class="ui-helper-hidden">
<span class="ui-button-text ui-c">Yes</span>
</div>
The two differences I described above, are not rendered in my previous version - there is no "ui-state-active" in the div class, nor "checked='checked'" in my <input />
I edited the HTML manually on my current (unclickable) version, and removed "checked='checked'" - this had no effect. I then removed the "ui-state-active" from my div class - and the button is now clickable.
I am still puzzled to why the HTML is now rendered differently, what could I of changed which would make this happen?
Thanks again.

Answer 1

After many hours, I finally figured out why...
As I said in my question,
SelectOneButton is an input component to select options using regular
buttons instead of radio buttons
SelectOneButtons are radio buttons.
In the same webpage, I also use radio buttons as on option using pretty similar code...
<p:selectOneRadio value="#{bean.result}">
<f:selectItems value="#{bean.options}" />
</p:selectOneRadio>
Now, I had trouble that when the user was presented with these radio buttons, none were selected. This allowed the user to return null. Now, I didn't want the user to be able to return null, hence the need for radio buttons - one or the other. So, I set #{bean.result} to the first element in #{bean.options} before the page is rendered, so when the user is presented with the buttons, the first is selected by default.
Hence, when the selectOneButton's were rendered, the first "button" was selected, and you couldn't press it.