The Data Provider dialog has a button named "Apply" whose purpose is to preview the data in the right section of the dialog. It should be noted that it is not necessary to click "Apply" to make transformations or anything else work. The user can simply set up everything and import the data without ever clicking "Apply". Therefore, it does not make sense to use the word "Apply" for this button; instead we should call it "Preview".
+ Sounds more clear.
Created attachment 199729 [details] Screenshot Not a fan. The preview is labelled as such above the frame. And clicking a button "Preview" does what action? Show it, go into, etc. I could rather live with "Update" with the argument that "Apply" typically applies the configuration in the actual document. But ultimately it's a bit bike-shedding to me.
We discussed the topic in the design meeting. Overall consensus was to remove the button entirely and apply changes immediately. Until then we may rename it to "Update Preview". See also bug 165229 for a similar discussion around the dialog.