bitcoin core – Can an unsynchronized node create a valid transaction?

Node A is holding a chain which is not in sync with the rest of the
nodes and node A decides to post a transaction.

If node A created transaction from valid unspent UTXO (which is valid on longest chain), the transaction will be valid. You don’t have to be even a node to send this valid, signed transaction, you can mail it to the node C which will include it into mempool.

The miners will pick up this transaction and add them to a block in
their own chain which is different than Node A’s chain.

As long as your node has communication with these miners, yes (there are different scenarios of “unsyncing”, I assume hardforks as well, but I guessed you meant orphan blocks mostly, or lack of recent blocks?).

So now when Node A looks at the network, will it just ignore its own
inconsistent chain and pick the miners chain?

No. If you are looking at top of chain A which isn’t in sync with the longest chain, where miners should add the transaction, your node won’t see it. The rest of the network on the longest chain will observe it though.

Will the transaction made by node A even show up in the blockchain?

Yes, in the longest chain.

Material Design – Android Application – How to indicate the existence of unsynchronized data

I have an Android application where users can create different types of content on different screens of the application. All content is synchronized with the server in a background thread. Normally this happens instantly, when new data is created, but if the device is offline, unsynchronized content may exist for a longer time.

For the user to realize that (so that he does not ask when comparing the content of the application and the content of the server through the web interface), I thought about showing an indicator somewhere in the application.

I'm not sure, how / where should I show such an indicator. I can not show the indicator in the action bar, because it is used for different things on many screens.

Ideas so far

  • Show the indicator as a lot type in the navigation drawer symbol ("burger" icon) but that would become quite small.
  • Use a notification, but since the indicator will disappear on its own, as soon as the synchronization is done, that seems a kind of abuse of the idea of ‚Äč‚Äčnotification.
  • It shows a colored line at the top or bottom of the action bar, but that does not explain itself.