ui: open a modal once when its button is double-clicked

A modal slides in over 250 ms, and until it covers the button that opened it the button still takes clicks, so a double click opened two copies (left-pane pages and most stacked center and right-pane pages on desktop, animated modals on Android). When a modal opens, the page it covers draws an empty pointerInput box over itself while it slides out; when a pane's first modal slides in, the empty page sliding out covers the view under the pane. The page sliding in already takes clicks, and nothing is blocked when a page closes.

apps/multiplatform/common/src/commonMain/kotlin/chat/simplex/common/views/helpers/ModalView.kt

@@ -9,6 +9,7 @@ import androidx.compose.runtime.*
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.input.pointer.pointerInput
 import chat.simplex.common.model.ChatController.appPrefs
 import chat.simplex.common.platform.*
 import LocalCardScreen
@@ -224,6 +225,10 @@ class ModalManager(private val placement: ModalPlacement? = null) {
       if (toRemove.isNotEmpty() && it == modalCount.value && transition.currentState == EnterExitState.Visible && !transition.isRunning) {
         runAtomically { toRemove.removeIf { elem -> modalViews.removeAt(elem); true } }
       }
+      // Until the opening modal covers the page that opened it, or the view under the first modal, a second click there would open it again
+      if (transition.targetState == EnterExitState.PostExit && it < modalCount.value) {
+        Box(Modifier.fillMaxSize().pointerInput(Unit) {})
+      }
     }
   }