They say "Patience is a Virtue", and we all know that our users (self included) have no patience. Often times we create a page that requires a bit of processing up front before the page is rendered. Normally, a page is called by a referencing page via a link, a button, or some other action. A problem arises when the next page is a slow page and the user is left on the original page with nothing happening. The user is tempted to perform the action again in a fit of desperation. Wouldn't it be nice if we could easily let the user know that some processing is going on and prevent them from performing additional actions? Luckily for us APEX has a Dynamic Action that allows us to do just that.
Demo Link
The "Submit Page" dynamic action has an option named "Show Processing" that can be set to "Yes" to enable the processing message (which is not really a message but an animated gif).
Example
Page 2 has a report that takes about 10 seconds to run.
Page 1 has a button, "P1_BUTTON1" which submits the Apex page. There is a branch that goes to page 2 when the button is pressed.
Create a dynamic action that will fire when the button is clicked.
Define the Action as "Submit Page". Enter P1_BUTTON1 for the Request/Button Name field and have the Show Processing select list set to "Yes".
This technique is also useful if we have a page process(es) that may take time executing when the page is submitted.
(Oracle Application Express) (Oracle APEX version 4.2)