Is there a way to keep a pane content (Collapse/Expand)?

[Valeriy]

If the splitter pane is collapsed,  its content is disposed and re-initialized again when the user expands the pane.

Is there a way to keep a pane content? 

[Nadezhda Tacheva]

Hi Valeriy,

Indeed, this is the current design of the Splitter and it is not possible to preserve the pane content when it is collapsed.

However, we have a logged request to expose such functionality in a future version of UI for Blazor:

Persist Splitter pane content after collapse and expand

I added your vote to increase the popularity of the item as we prioritize the enhancements based on the community demand. You may additionally follow it to get status updates.

Regards,
Nadezhda Tacheva
Progress Telerik