Yep ! Thanks for replying BTW 
I tried several solutions:
- All Datasources script loaded in doBackgroundProcessing (Called be Startup): All crosstabs refreshed at the same time
- Quick DS loaded at runtime, long ones with doBackground: Corresponding crosstabs rendered all at the same time again
- All DS script loaded, DS_1 loaded in doBackground, DS_1 On result changed: DS_2.load(), DS_2 On Result changed: DS_3.load() ....: DS_1 is loaded in background, but the application is not displayed until the last datasource is loaded, and lots of messages are displayed (Second attempt to execute event handler "On Result Set Changed" for data source DS_1 was rejected, because it can cause an execution cycle.)
- Same as before, but calling doBackgroundProcessing in the Datasource onResultChanged, If DS_1.isInitialized() Then DS_2.load() x 16 for each datasource (to load subsequent datasources): Works, but the application slows until it is frozen for 2-5 seconds for each rendering. DS_7 is one of the long runtime, and when it is being loaded, the application freeze completely and all remaining crosstabs are rendered at the same time
doBackgroundProcessing called first in the onStartup, and in each onResultChanged:
if (DS_1.isInitialized()) {
DS_2.loadDataSource();
} else {
DS_1.loadDataSource();
}
if (DS_2.isInitialized()) {
DS_3.loadDataSource();
}
if (DS_3.isInitialized()) {
DS_4.loadDataSource();
}
if (DS_5.isInitialized()) {
DS_6.loadDataSource();
}
if (DS_6.isInitialized()) {
DS_7.loadDataSource();
}
At first, the last solution crashed my application with only 4 datasources, but now works.
Ultimately, the first solution gives me empty crosstabs with a loading state (showLoadingState), and are rendered at the same time, which is better than having an application frozen several times.