This will allow you to keep toggling the size of A between 70 and 100%. Live example:
http://jsfiddle.net/LX484/
HTML:
<div id="log">
<button id="toggle">Toggle A's size</button>
</div>
<div class="k-content">
<div class="a">A</div>
<div class="b">B</div>
</div>
JS:
$(function () {
setupSplitters();
$('#toggle').click(function () {
var splitter = $('.k-content').data('kendoSplitter');
var curSize = splitter.size('.a');
splitter.size('.a', curSize === '100%' ? '70%': '100%');
});
});
function setupSplitters() {
$('.k-content').kendoSplitter({
orientation: 'horizontal',
panes: [
// A
{
resizable: true, collapsible: false, max:'90%', min:'33%' , size: '70%'
},
// B
{
resizable: true, collapsible: false, max:'67%', min:'10%',size: '30%'
}]
});
}