GH-3720 Fix UI inconsistencies with Modplatforms

Fixes GH-3118
Fixes GH-3720
Fixes GH-3731

Icons and Ok button state will now switch consistently when moving
between tabs. ATLaunchers packlist is now no longer redownloaded
each time you open its Tab. All lists are striped now. And all
search and filter fields now have a placeholder text.

application/pages/modplatform/flame/FlamePage.cpp

@@ -18,6 +18,8 @@ FlamePage::FlamePage(NewInstanceDialog* dialog, QWidget *parent)
     ui->packView->setModel(listModel);
 
     ui->versionSelectionBox->setMaxVisibleItems(10);
+    // fix height for themes that dont respect max visible like fusion
+    ui->versionSelectionBox->setStyleSheet("combobox-popup: 0;");
 
     // index is used to set the sorting with the curseforge api
     ui->sortByBox->addItem(tr("Sort by featured"));
@@ -157,6 +159,12 @@ void FlamePage::suggestCurrent()
         return;
     }
 
+    if (selectedVersion.isEmpty())
+    {
+        dialog->setSuggestedPack();
+        return;
+    }
+
     dialog->setSuggestedPack(current.name, new InstanceImportTask(selectedVersion));
     QString editedLogoName;
     editedLogoName = "curseforge_" + current.logoName.section(".", 0, 0);