One thing to test is if you explicitly set the size on the chart via the "chart.setSize(width, height)" method before you render the chart, and then see if that makes a difference. If that doesn't make a difference, then I'm guessing that you may be running into an issue with the default image converter that the HighSoft guys provide for the exporter, so you may want to reach out to them for advice:
I am using GWT Highcharts 1.5.0 with Highcharts 2.3.3. When I am trying to download the image as PDF, legends are not displayed properly.
Any suggestions ?
One thing to test is if you explicitly set the size on the chart via the "chart.setSize(width, height)" method before you render the chart, and then see if that makes a difference. If that doesn't make a difference, then I'm guessing that you may be running into an issue with the default image converter that the HighSoft guys provide for the exporter, so you may want to reach out to them for advice:
http://www.highcharts.com/support