I have been doing experiments with the very nice text costume feature. I like it a lot! Unfortunately, it seems impossible to make a text which covers more than half the stage size.
e.g. With the default stage size of 480 px wide, if you try to make a text costume with the text "012345678" in size 72, you will only see that the text is rendered until half of the 5 character and the resulting costume size is +/- half the stage size.
The workaround seems to be to first switch to a stage which is twice as wide, wait a for a short time, create the costume, and make the stage smaller again.
Even though this is working, it is not an ideal workaround for my project in which I render texts at runtime. It is perfectly possible to change the stage size at runtime, but this is obviously visible.