Not sure if this is a bug but it seems there are some different behaviors between the latest p5 libraries (starting with 0.4.18) and the version that comes with the p5 editor.

When developing using the editor, pmouseX/Y seems to update with the new frame so if the mouse stops moving pmouseX/Y will equal mouseX/Y on the next frame. However, with 0.4.18 and 0.4.19, when the mouse stops moving pmouseX/Y does not equal the current mouseX/Y values.

Is this the desired behavior?