Photoshop and Sketch 3

Can I design my app in photoshop or Sketch 3 and then implement that design in Xojo ? In other words can you make a custom UI in Xojo ?

you can use a graphics editor to create a background image… but not to layout windows, and controls etc.

You canc reate a mockup. I create mine on the back of shop tickets, snow mail letters, etc… to recall them once I am able to create it with Xojo IDE Interface Editor (Window Editor).

Days ago, I woke up from my afternoon nap to write a window design (paper / pen), then go back to finish my nap ! At dinner time, I woke up and implement the pen draw interface… and then I started to put code in the Controls…

You can also create your interface using a paint / draw program, load the image / set it in the window background and place your interface (traditional or Canvas…) above it, then remove that mockup image once your interface is over.

If you are asking about a completely custom interface, for example with triangle shaped controls, then yes, but be ready for some work.

You can create the image and set it as the background of a window.
Then you need to detect mouse clicks on the active areas… that might be easiest to do by placing canvases ove the active spots, and detecting mouse clicks on the canvas objects.
(Easier than detecting a click on the whole window and using co-ordinates to work out what was intended.

You can draw on the screen.
You can add text to the screen.

You wont be able to do text input on the screen unless you display a text box / area or add such a ‘real’ control at design time.

And you will probably need some work to implement visual cues about what was clicked, otherwise your interface will feel as responsive as a brick wall.

Your imagination is your limitation, you could have text flowing around the outside of a circle or along a wobbly line as you type. The problem is, you’ll need to code that type of stuff by hand.