Remote fixes

Because right-click for returning from remote mode was not working after remote UI merge, it has been disabled for now.

Fixed drag and drop regression after remote UI Merge.

The remote port is not editable in a range from 1024 to 65535 to prevent misconfiguration.

Disabled automatic LTA option until getting this better integrated on advanced options by disabling AdES combobox blocks in later UI changes.

The textarea for custom signature text has been improved. Now the tab shift+tab keys will traverse it like other fields instead of adding a tab character as text, which caused invalid PDF character in some reported cases. Also, some users didn't know this field was editable, so improved textarea experience on Windows by using same font as single-line text controls and by adding border and re-adding opacity on GTK.