“An invalid or illegal string was specified” Exception in GWT
While working with canvas (drawing stuff on it) in GWT, suddenly and in a seemingly unpredictable manner I got following error message now and then from within the GWT framework code:
com.google.gwt.core.client.JavaScriptException: (NS_ERROR_DOM_SYNTAX_ERR): An invalid or illegal string was specified;
Again, GWT tricked me into thinking I am writing Java code and made me forget about that it is going to be compiled into Javascript. And because of the latter, a division by zero does not throw an DevisionByZeroException, no, it returns NaN even for native data types (there is no differentiation between double and Double in Javascript – there is only the object-version of double, which can be of value Double.NaN).
But also GWT was not prepared to handle Double.NaN. When calling canvas.getContext().drawImage(image,x,y) and one of x and y or both were Double.NaN I got the error message shown above. If you got the same… you know what to do: check all devisions in your code for potential devisions by zero!!
Flickering Screen with ATI Radeon X1400 and Ubuntu
EDIT: ATI Radeon X1400 seems to work fine with Ubuntu 11.04.
There is another fix to the “well known” issues with the ATI Radeon X1400 and Ubuntu 10.04 to 10.10 besides the one posted about one year ago (see here).
The previous fix kept the graphics card working normally but harmed the overall operating system’s stability, so here is another fix based on disabling all 3D features of the device to get rid of the flickering screen.
It’s up to you to choose what you are able to live without
a) The desktop settings panel and “Segmentation fault” errors now and then, or
b) 3D acceleration (does not harm video playback or any other basic OS functionalities)
For solution a) see this.
For b) create this file: /etc/modprobe.d/radeon-kms.conf — and add following content
options radeon modeset=0
Solution found here (in German).
