Webviewer and D3 charts problem

Hi

I am experimenting with Treemaps using the D3.js and D3plus.js libraries in FMPro Advanced 15 and the Webviewer (OSX 10.11). D3plus.js is really nice as it makes it much much easier to implement a Treemap using a simple JSON object containing your data. But sometimes thing don't work as expected and I don't fully understand why:

- I invoke D3plus code in a FileMaker global text field, as a data:url, iincluding the D3 and D3plus libs in an external reference (I don't include the complete code in the text field). So these are loaded at runtime.

- this works fine, but sometimes the treemap hich is a complex SVG graphics generated by D3) defaults to a 200x200 px area.  

Reloading the webviewer usually fixes the problem (or manually changing the HTML body, by adding a space, wihich forces the webviewer to refresh its contents). But my question remains: why and when does this happen? My guess is that at times the Javascript code is not loaded in the proper order, but I can't figure out how to influence this.

The D3.js is invoked prior to D3plus.js, and all D3plus code is executed after these libraries are invoked.

Anyone with similar issues?