Resolves: tdf#115964 force password dialog to center on parent size request

this is similar to...

commit d17d9500
Date:   Tue Apr 16 14:49:46 2019 +0100

    tdf#124597 template select dialog launched before parent gets final size

where the dialog is launched before its parent window has got to its final size

Change-Id: I0f54a8da482ed75fa939e230b69c0eb918782bf5
Reviewed-on: https://gerrit.libreoffice.org/70943
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

uui/source/passworddlg.cxx

@@ -41,6 +41,9 @@ PasswordDialog::PasswordDialog(weld::Window* pParent,
     , aPasswdMismatch(Translate::get(STR_PASSWORD_MISMATCH, rLocale))
     , rResLocale(rLocale)
 {
+    // tdf#115964 we can be launched before the parent has resized to its final size
+    m_xDialog->set_centered_on_parent_geometry_request();
+
     if( nDialogMode == task::PasswordRequestMode_PASSWORD_REENTER )
     {
         const char* pOpenToModifyErrStrId = bOpenToModify ? STR_ERROR_PASSWORD_TO_MODIFY_WRONG : STR_ERROR_PASSWORD_TO_OPEN_WRONG;