Let a downloaded program be downloaded again

The button disappeared the moment anything landed, and nothing else on
the window asks for that download. So a machine that got the processor
build before its graphics driver was installed can never be given the
Vulkan one, and nobody can pick up a newer whisper.cpp either: both of
those are the same missing control.

It reads "Download again" once a copy is here, and stays hidden while a
system one is on the PATH, because that is the copy that would run.

dikte/settings_ui.py

@@ -349,10 +349,18 @@ class LocalModelBox(QGroupBox):
         path = ggml.program_path(self.program)
         if not path:
             self.program_label.setText(t("Not installed."))
+            self.install_button.setText(t("Download"))
             self.install_button.setVisible(True)
             return
-        self.install_button.setVisible(not ggml.installed_program(self.program)
-                                       and not ggml.system_program(self.program))
+        # A copy that is here is not a copy that is right. whisper.cpp releases
+        # every few weeks, and a graphics card installed after Dikte was
+        # changes which build this machine should be running; the button was
+        # hidden the moment anything landed, and nothing else on this window
+        # asks for the download again.
+        self.install_button.setText(t("Download again")
+                                    if ggml.installed_program(self.program)
+                                    else t("Download"))
+        self.install_button.setVisible(not ggml.system_program(self.program))
         if ggml.system_program(self.program):
             # Worth saying which one is running: a distribution package is built
             # for this machine and may reach the graphics card, while the