Spend up to 4 hours researching the feasibility and benefits/drawbacks of a partial or full upgrade of extJS version.
Moving from the current version of ExtJS 4.1 to any major release is not feasible within the allotted sustaining engineering budget. The level of effort is significant.
We are not able to download older (non-current) versions of ExtJS (e.g. 4.3) without purchasing a license.
I was able to find a copy of ExtJS 4.2 but can't confirm that it is a valid copy. I did try it and there are a number of changes to SSP that need to be made to make this version work. It was deemed not work the effort for a small incremental upgrade.