also if you continue typing it will overwrites the previous content inside the cell
and this is annoying

Confirmed in master. The direction toolbar buttons are confirming cell entry, unlike alignment buttons &co.

Bug confirmed on 4.0.2.2, updating bug's version.

Looks like the code at the top of ScFormatShell::ExecuteTextDirection kicks out of edit mode

if ( GetViewData()->HasEditView( GetViewData()->GetActivePart() ) )           
{                                                                             
    SC_MOD()->InputEnterHandler();                                            
    pTabViewShell->UpdateInputHandler();                                      
} 


ScFormatShell::ExecuteAlignment on the other hand doesn't kick out of edit mode.

I have a proposal at https://gerrit.libreoffice.org/#/c/3450/ as an alternative to that of https://gerrit.libreoffice.org/#/c/3406/

Caolan McNamara committed a patch related to this issue.
It has been pushed to "master":

http://cgit.freedesktop.org/libreoffice/core/commit/?id=7c3db8a660fbbcfca277e5cf22a3987c35e656d0

Resolves: fdo#63592 changing text direction exits edit mode



The patch should be included in the daily builds available at
http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More
information about daily builds can be found at:
http://wiki.documentfoundation.org/Testing_Daily_Builds
Affected users are encouraged to test the fix and report feedback.

seems to be fixed

Fix verified on a build from master.

Reopening 
this bug patch cause another problem
problem is:
change your numerical type to context (tools>option>language setting>complex text layout)

1-type  123 in LTR mode 
2-change to RTL mode 
3-problem is calc doesn't update the view so you have to get out from edit and enter again then it will be updated.

i will upload a new patch after minutes.

you can check the proposal patch here
https://gerrit.libreoffice.org/#/c/3629/

abdulmajeed ahmed committed a patch related to this issue.
It has been pushed to "master":

http://cgit.freedesktop.org/libreoffice/core/commit/?id=5a8a57703cad29ec2865390f3ced34af0e82b33f

fdo#63592 Solve context numerical problem when changing text direction



The patch should be included in the daily builds available at
http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More
information about daily builds can be found at:
http://wiki.documentfoundation.org/Testing_Daily_Builds
Affected users are encouraged to test the fix and report feedback.

Fixed verified on a build from master (4.1 branching point).