ThemeEditor: Update theme path on theme load

Prior to this change, the 'Save' action was saving a file to the startup
path (or just showed a File Picker dialog) if a file has been opened
by the Open action or by drag-n-dropping a file to the program.

Userland/Applications/ThemeEditor/PreviewWidget.cpp

@@ -105,6 +105,8 @@ void PreviewWidget::set_theme_from_file(String const& path, int fd)
 
     m_preview_palette = Gfx::Palette(Gfx::PaletteImpl::create_with_anonymous_buffer(theme));
     set_preview_palette(m_preview_palette);
+    if (on_theme_load_from_file)
+        on_theme_load_from_file(path);
 }
 
 void PreviewWidget::paint_event(GUI::PaintEvent& event)

Userland/Applications/ThemeEditor/PreviewWidget.h

@@ -23,6 +23,8 @@ public:
     void set_preview_palette(const Gfx::Palette&);
     void set_theme_from_file(String const& path, int fd);
 
+    Function<void(String const&)> on_theme_load_from_file;
+
 private:
     explicit PreviewWidget(const Gfx::Palette&);
 

Userland/Applications/ThemeEditor/main.cpp

@@ -130,6 +130,10 @@ int main(int argc, char** argv)
 
     auto& file_menu = window->add_menu("&File");
 
+    preview_widget.on_theme_load_from_file = [&](String const& new_path) {
+        path = new_path;
+    };
+
     auto save_to_result = [&](FileSystemAccessClient::Result const& result) {
         if (result.error != 0)
             return;