优化Lora信道下拉框布局

gateway_config.py

@@ -321,7 +321,7 @@ class GatewayConfigTool(QMainWindow):
 
         lora_layout.addWidget(QLabel("信道:"))
         self.combo_lora_fc = QComboBox()
-        self.combo_lora_fc.setSizeAdjustPolicy(QComboBox.AdjustToMinimumContentsLengthWithIcon)
+        self.combo_lora_fc.setFixedWidth(200)
         lora_freqs = []
         fc_hz = 410100000
         ch_idx = 1
@@ -332,9 +332,12 @@ class GatewayConfigTool(QMainWindow):
             ch_idx += 1
         for freq, desc in lora_freqs:
             self.combo_lora_fc.addItem(desc, freq)
-        self.combo_lora_fc.view().setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOn)
-        self.combo_lora_fc.view().setMinimumHeight(200)
-        lora_layout.addWidget(self.combo_lora_fc, 1)
+        self.combo_lora_fc.setMaxVisibleItems(20)
+        self.combo_lora_fc.setStyleSheet(
+            "QComboBox { combobox-popup: 0; }"
+            "QComboBox QAbstractItemView { max-height: 500px; }"
+        )
+        lora_layout.addWidget(self.combo_lora_fc)
 
         self.btn_lora_fc = QPushButton("发送")
         self.btn_lora_fc.setFixedWidth(60)
@@ -342,6 +345,8 @@ class GatewayConfigTool(QMainWindow):
         self.btn_lora_fc.clicked.connect(self.on_lora_send)
         lora_layout.addWidget(self.btn_lora_fc)
 
+        lora_layout.addStretch()
+
         config_layout.addWidget(lora_group)
 
         # -- 下方：日志区 + 自定义指令 --