Here’s a list of common issues and their solutions:
Widget flicker
Between any two yield from _ statements that can return, there must be exactly one yield statement. If there is none, elements may get duplicated in a frame after triggering an action. If there is more than one yield statemet, elements may momentarily disappear.
Most of the time, it is enough to slap a yield at the end of each loop (example). I don’t think this bit of syntactic inconvenience can be solved without introducing other quirks.
Event congestion
On each frame, at most one action can get triggered from an concur.core.orr block. Actions from first sub-widgets are prioritized, and any actions from further sub-widgets will get thrown out. This is a problem when there are rapidly-firing widgets, such as video playback.
Push the widgets with lower priority down the widget lists, or swap the congesting orr function for multi_orr. concur.core.multi_orr returns a list of all fired events, which trades correctness for some boilerplate. Typically, the top-level widget list is multi_orr, while the lower levels can be orr.
Asynchronous computations
In other versions of Concur, all widgets are triggered asynchronously. This may not be practical in Python, due to the incompatibility in design of ImGui and async generators. Synchronous generators are used instead, which means that all widget code is run in the main thread. Asynchronous code must be explicitly run in a background thread, which is easily achieved by passing a future into the concur.core.Block function. See the timers example for details.
Window flicker on docking
If a window starts to flicker when it is docked into a tabbed dock, it is caused by nested window calls (#33). Windows should not be nested. Use orr([window(...), window(...)]) instead.