Here the keyboard control input is inconsistent. Usually a user will tab to the next control or control group ie arrow buttons, the arrow keys should be for navigation within a control/control group. I thought the idea of a preview was to see the changes made as you enter them. And the 'Top' value is not previewed until you click something else. If you want to use the custom position, if you type your offset in the 'left' box, it is not previewed until you have tabbed or clicked the 'top' box.
The combination of mouse clicks and keyboard inputs are not consistent and not intuitive. So I clicked on the Preset Position radio button again and clicked on the down arrow button, my text moved straight back to the starting position in the top left corner. Next, I just wanted to move it down a little more so I pressed my keyboard down arrow button and pressed enter, instead of moving the text down a little the program put the focus on the Custom Offset Radio button which disabled the arrow buttons. Near the bottom of the image I pressed the right arrow key on my keyboard, the RH arrow button was selected (in focus), then again I pressed and held enter until the text was positioned on the RH side of the image.
So, code does exist for this, the developer just needs to ad an event handler that recognises when the LH mouse button being held down. If you click on an arrow button and then hold down the enter key the text will move constantly until you release the enter key.
To move the text you have to constantly keep clicking on the arrow direction buttons, one click one small move for your text, you cannot click and hold down the LH mouse button to constantly move your text. In my example I want to add text to the bottom right hand corner of the picture.
I like this software but it has a couple of really niggling things which could easily be remedied by the developer.