Some programs get stuck when I click "Open..." or "Save as..."

[DJYeh]

Freshly installed Ubuntu 18.04, with Hime from the Ubuntu software center. Programs like Luminance HDR, Mendeley, mGBA and OpenShot will freeze when I click "Open..." or "Save as..." Problem disappears when I change the input method to iBus.

Error message:
GLib-GObject-WARNING **: cannot register existing type 'GtkIMContext'
GLib-CRITICAL **: g_once_init_leave: assertion 'result != 0' failed
GLib-GObject-CRITICAL **: g_type_register_dynamic: assertion 'parent_type > 0' failed
GLib-GObject-CRITICAL **: g_object_new_with_properties: assertion 'G_TYPE_IS_OBJECT (object_type)' failed