[LVGL] If the "selected" property of a roller or dropdown is "assignable", keyboard input doesn't work anymore

[CarstenNeubert]

Describe the bug
If the "selected" property of a roller or dropdown widget is assigned to a local or global variable, it doesn't seem to be possible to control the widget by keyboard or encoder input anymore. Mouse and touch input still work.

My expectation would be that the connection to the assigned variable is bidirectional and changing the variable changes the widget, while controlling the widget changes the variable. This is how it works for widgets like sliders.

Is it possible, as a workaround, to get the selected item of roller using a flow expression? As far as I understand, making it an assigned property is the only way to get the data.

To Reproduce
Steps to reproduce the behavior:

1. Create a roller or dropdown and assign it to a group that is controllable via keyboard/encoder
2. Test input -> widget is controllable by keyboard, encoder, mouse, and touch
3. Create a variable
4. Switch the "Selected" property to "Assignable" and set it to the variable
5. Test keyboard/encoder input -> widget receives input but immediately jumps back to old value
6. Test mouse/touch input -> still works

The jumping back is visible for a dropdown, while the roller doesn't react at all. Even sending key events directly to the widget does not work anymore.

Desktop (please complete the following information):

• EEZ Studio version 0.24.0 on Windows

** LVGL version (if used)**

• 9.x

[mvladic]

I can't reproduce this issue. I tested with both LVGL v9.2.2 (this is the version that Studio simulator is using) and v9.3.0. Here is my project:

lvgl_dropdown_selected.zip

You can test it inside Studio using simulator. In simulator, encoder is simulated with the mouse wheel. Use mouse wheel to move from widget to widget and then use mouse wheel click ("middle button") to switch a widget to the edit mode. When a widget is in the edit mode it is drawn with the red frame. In the edit mode you can make a selection. Here is how it looks:

[CarstenNeubert]

You're right. I missed the middle mouse button to enter edit mode...

Is there a similar requirement to make keyboard input work? Because this is what I get when I switch both widgets in your project to the keyboard group: