If you are using loadhtml to show text then you can prevent text selection via some CSS.
If you are showing a webpage and you have access to that page content then you can prevent text selection via CSS or javascript.
If you are showing a webpage and you don't have access to that page content then you can use WebViewExtra to execute javascript to prevent text selection.
If you don't know how to do that in css or javascript then tell me which one you need I'll post sample css or javascript code.
Then just add this css inside head tag of that html file.
HTML:
<style>
* {
-webkit-user-select: none;
}
</style>
Though this following code sample will work for all the cases (local and remote webpage).
B4X:
Private wve As WebViewExtras
wve.Initialize(webview1)
wve.JavaScriptEnabled = True
wve.LoadUrl(xui.FileUri(File.DirAssets, "elem2.html"))
Sub webview1_PageFinished (Url As String)
wve.ExecuteJavascript("document.querySelector('*').style.webkitUserSelect = 'none';")
End Sub