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<!-- Describe the issue -->
Expected behavior
The dialog should display actual folders and files on the filesystem.
<!--- What behavior did you expect? -->
Actual behavior
It doesn't allow selection of "Computer" or "Recent Places" in Look in and only starts showing directories when clicking on the parent directory icon. Selecting on a directory puts that directory in the "File name" and only some children directories are shown. No files are shown. This screenshot happened after selecting the "Documents" directory and zero directories or files are shown within the Documents directory, however sometimes one directory is shown. It seems as though a small subset of directories are being treated as though they are both directories and files. I haven't tried saving anything as I have no idea what it would try saving to.
Other programs on the machine have save dialogs which work correctly, including the "Export Transaction History" dialog in Peercoin 0.8.4 64bit.
<!--- What was the actual behavior (provide screenshots if the issue is GUI-related)? -->
To reproduce
Clicking on the Export button for transactions consistently displays this broken dialog.
<!--- How reliably can you reproduce the issue, what are the steps to do so? -->
System information
Using v0.19.0.1 (64-bit) for Linux downloaded from https://bitcoin.org/en/bitcoin-core/
<!-- What version of Bitcoin Core are you using, where did you get it (website, self-compiled, etc)? -->
Linux Debian Stretch (9.11 and fully uptodate) x86_64 i7-4770 CPU KDE 5.8.6
Potentially relevant debug.log line:
GUI: QObject::connect: Cannot queue arguments of type 'size_t'
(Make sure 'size_t' is registered using qRegisterMetaType().)<!-- What type of machine are you observing the error on (OS/CPU and disk type)? -->
<!-- GUI-related issue? What is your operating system and its version? If Linux, what is your desktop environment and graphical shell? -->
<!-- Any extra information that might be useful in the debugging process. -->
<!--- This is normally the contents of a `debug.log` or `config.log` file. Raw text or a link to a pastebin type site are preferred. -->
