I use Okular to sign hundreds of PDF documents each month using the "freehand line" tool. It has great resolution and works perfectly using a sketch pad.

My issue is there is no tool lock. In other words, when I sign a document, once my pen leaves the sketch pad, I must select the "freehand line" tool again and again to cross a "T" or dot an "i".

Is there a tool lock that I may be unaware of, or may I suggest this as an addition to future releases of Okular?

Thank you.

If you double click on the tool on the annotation toolbar instead of using a single click, the tool will stay enabled until you select double click:

With a single left mouse button click on an annotation tool button you can use a tool once. If you e.g. want to highlight all important parts of a text, activate that tool permanently by double clicking on the tool button. Press the Esc key or click the tool button again to leave the permanent mode.

(from https://docs.kde.org/stable5/en/kdegraphics/okular/annotations.html)