Give keyboard focus to the search input field when showing dialog

Previously, the Help button got the keyboard focus because the focus
chain is messed up because the button box is created before the
page.

GnuPG-bug-id: 6095

src/conf/groupsconfigdialog.cpp

@@ -25,6 +25,7 @@
 #include <Libkleo/DocAction>
 
 #include <QDialogButtonBox>
+#include <QLineEdit>
 #include <QPushButton>
 #include <QScrollArea>
 
@@ -34,6 +35,7 @@ class GroupsConfigDialog::Private
     GroupsConfigDialog *const q;
 
     GroupsConfigPage *configPage = nullptr;
+    bool initialFocusWasSet = false;
 
 public:
     Private(GroupsConfigDialog *qq)
@@ -48,6 +50,21 @@ public:
         saveLayout();
     }
 
+    void setInitialFocus()
+    {
+        if (initialFocusWasSet) {
+            return;
+        }
+        // this is a bit hacky, but fixing the focus chain where the dialog
+        // button box comes before the page, which causes the first button in
+        // the button box to be focussed initially, is even more hacky
+        Q_ASSERT(configPage->findChildren<QLineEdit *>().size() == 1);
+        if (auto searchField = configPage->findChild<QLineEdit *>()) {
+            searchField->setFocus();
+        }
+        initialFocusWasSet = true;
+    }
+
 private:
     void saveLayout()
     {
@@ -125,6 +142,8 @@ QString GroupsConfigDialog::dialogName()
 
 void GroupsConfigDialog::showEvent(QShowEvent *event)
 {
+    d->setInitialFocus();
+
     KConfigDialog::showEvent(event);
 
     // prevent accidental closing of dialog when pressing Enter while the search field has focus