We are actually working on a prototype capable of dealing with xlsx files directly without the need of the MS Excel application.
The main advantage is to work with xlsx in all existing plateformes (web, desktop, mobile) with no more application than LiveCode. As another advantage, other applications such as Open Office, would be capable to open xslx files, so we will not be restricted to MS Excel only.
In the other hand, warning the developer something is wrong in the file is more difficult than when the file is created and so controlled on the fly by MS Excel. For example the Excel Lib in its actual form is capable to return an error when a formula is wrong because the formula is interpreted on the fly by MS Excel during the building of the worksheet. Working with the xlsx file structure is low level, so some errors will be returned only when MS Excel will interpreted the file once one opening it. Debugging the creation of a complex workbook would quickly become a challenge or a nightmare.
Even if the prototype has been created from scratch, the idea at this point is to include the code of the xlsx editor in the Excel Lib and to use more or less the same commands and functions we have already in the Excel Lib. We would have a direct file "writting mode" and a "controlling mode". That way, developers would be use the "controlling mode" for debugging purpose, before to use the "writting mode" for the final application.
Here is the idea!
Now we are just in the beginning of this project and far to have included all the features we have in the actual library, such as charts, slicers or pivot tables features.
So far we are capable to create or to open a xslx file and put strings, numeric values and formulas in cells of the first worksheet. The code we have is designed for managing several workbooks at the same time allowing at term to copy sheets from a workbook to another, for example, but this will be another step(s). The next steps are to support very basic things, such as font styles, then cell styles.
If you have an interest in this project, feel free to drop me a line with what you are waiting from the editor or if you would have the need of other editors for Word or Powerpoint. Donations are also welcome and can help to speed up the development.
We have opened a new line in the "In Progress" topic to keep you inform on where we are in this project.